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Countertop Geology: Marble and quartzite and granite, oh my!

posted by: karin_mt on 05.25.2013 at 09:51 am in Kitchens Forum

This is round three of the Great Rocks Thread! It appears we at GW have a large appetite for discussing and sharing pictures of rocks.

Please post your rock questions here. I've copied the first post from Rocks 102 here to lay the foundation.

Quartzite and marble are hopelessly (deliberately?) mixed up in the decorative stone industry. My point, aside from just loving rocks, is to help folks learn how to tell the difference between the two so you are not at the mercy of a sales rep when a multi-thousand dollar purchase hangs in the balance.

Quartzite is much harder than marble and will not etch when exposed to acids. You can tell the difference between quartzite and marble by doing the scratch test.

Take a glass bottle or a glass tile with you when you go stone shopping. (Glass tile idea is courtesy of MaggiePie11, what a good idea!) Find a rough, sharp edge of the stone. Drag the glass over the edge of the stone. Press pretty hard. Try to scratch the glass with the stone.

Quartzite will bite right into the glass and will leave a big scratch mark.
Any feldspar will do the same. (Granites are made mostly of feldspar)

Calcite and dolomite (that's what marble and limestone are made of) will not scratch. In fact you will be able to feel in your hand that the rock won't bite into the glass. It feels slippery, no matter how hard you press.

PS - don't press so hard that you risk breaking the glass in your hand. You shouldn't need to press that hard!

For reference, here are links to the other rock threads, in which many types of rocks have been discussed. If you read through both of these threads you will earn an honorary degree in Kitchen Geology.

Rocks 101: The Lowdown on Super White.

Rocks 102: Marble, Quartzite and Other Rocks in the Kitchen.

With that, let the rock conversations continue!
-Karin

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #147)

posted by: karin_mt on 05.25.2013 at 09:35 am in Kitchens Forum

Hi Karen,

Cool! A new type of rock to consider, I like that!

I like slate and it is durable and should hold up well in a kitchen. I especially like the idea of using your local slate in your kitchen, which would add an interesting note to your project.

From the durability point of view, there are two small caveats. The first is that slate is a rock with prominent layering and those layers are also planes of weakness. Granite (true igneous granite) and marble are equally strong in all directions so fabricators can sculpt edges and corners without worry of the layered structure creating a problem. I'm sure the fabricator has experience handling this, but it's something I'd ask about.

The second thing to look for is the degree of metamorphism in this particular slate. Like quartzite, slate is a metamorphic rock and may have undergone a range of heat and pressure. Some slates are weakly metamorphosed and split easily along the layers. Others have been heated and squeezed more and are extremely tough and durable. I'd want to make sure this slate falls on the strong end of the spectrum. The way I tell the difference here is to have a sample and break it with a hammer. By doing that you can observe how much effort it takes to break and how likely the rock is to split along its layers.

That aside, have you gotten a sample to check out the aesthetic qualities? What color is this slate? I like the subtle shine that slate has, and the layers lend a neat, linear texture to the rock. I also like working with slate for landscaping purposes. Our rock yard has some Pennsylvania Bluestone which I would just love to use for patio rocks, but I can't live with that type of long-distance shipping when we have plenty of local Montana rocks to choose from.

This thread is about to run out but I will start a new one so that you can post follow-up questions. It would be good to see a photo of this slate if you have one.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #116)

posted by: karin_mt on 05.02.2013 at 08:58 pm in Kitchens Forum

Hi Maggie,

First of all, using a glass tile (instead of, say, a whiskey bottle) for your scratch tests is very smart. A lot less conspicuous.

So it seems the crux of your question is, can a slab have both calcite and quartz in it? The answer for the most part is no. Usually it's going to be one or the other with the exception of veins. The veins can be either calcite or quartz and they are not always the same as the rest of the rock. Aside from that, marble is not likely to be blended with quartzite. Not to say that it could never happen, but that is not the way these rocks typically form.

The other answer is yes, several rocks are going by the name Super White and some are marble and some really are quartzite. Although it seems the majority are marble. Similarly several rocks that are the same thing have different names (a la Grey Goose). The names are just ridiculous, so probably the safest thing you can do is ignore the name and take each rock for how it looks and how it responds to your tests.

Since I see that you are a sharp student about these rocks, see if you can visually tell the difference between quartzite and marble. Even though they look nearly the same, the quartz is glassier and the calcite has a softer luster and is a bit duller. If you do the scratch tests on a few slabs, note the results and then really look at the rock you might be able to see the differences visually. That would be one way to make yourself feel better about knowing which rock you've got. I too would want to be super careful so I applaud how thorough you are being.

Good luck!
Karin

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #114)

posted by: maggiepie11 on 05.02.2013 at 04:37 pm in Kitchens Forum

hi karin! i don't mean to beat this topic to death, though there's clearly a lot of interest so hopefully this isn't an annoying question or point of clarification...

i've read each and every message on the 150 post thread and every message on this thread (probably two or three times each--we're talking a true thread stalker here!) and one thing i'm still not 100% clear on is whether Super White is 2 different beasts - one in marble form and one in quartzite form, or if any given slab can be a bit of both.

I get that you need to do the scratch test and acid test. I've done part 1 and each slab in the stack at this particular granite slab warehouse easily scratched the glass - 2 sample scratches shown below. i was shocked how easily it scratched the glass, and how other marbles there laughed at trying to scratch the glass. :) by the way, i took a couple sample glass tiles which looked less out of place than a glass bottle as i walked through the slab warehouse.

 photo 20130502_150902.jpg

so when the time comes, i plan to get a sample and go at it with every form of acid i can think of. i guess my concern is that i could get a sample piece that behaves more like quartzite and then the rest of that slab may be more like marble. is that possible? or back to my initial point--do you think there are 2 stones out there that look identical just with different compositions? it seems to me, though i can't find those posts now, that there were a couple folks who tested their samples and were shocked when it seemed like quartzite but then etched when they got it installed.

here's the slab in case you want to see. i lust over the deeper grey tone of this with the chunky white spots, but my husband and i are very tough on our counters, and we have 2 little ones. etching would be devastating to us.

 photo 20130426_125218.jpg

would love to get your opinion.
thanks for all the great information and questions by all.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #110)

posted by: karin_mt on 04.28.2013 at 11:09 am in Kitchens Forum

Hi AZMom,

Whoa, aren't these fun!

Let's see - Slab #1 retains its original layering, but during metamorphism the rock was compressed and heated. The heating allowed the rock to bend into a ribbon-like texture, sort of like taffy would. This rock was only mildly compressed, so the original layers are still there, but you can see they've been wrinkled up when the rock was shortened. (Imagine pushing on a throw rug from either end - it just ripples a bit.) The orange hue is from some iron oxide in the cement that was in between the quartz grains when it was originally deposited. For example, many sandstones in the Southwest have a similar orangey-brown color.

Slab #2 underwent a more turbulent metamorphic process. For starters, the original rock had more variation in composition so you have layers of different colors. Then the rock was really tortured during metamorphism - it was compressed so much that the layers wrinkled, stretched, then broke apart and began to drift away from each other. But if you pick a prominent layer like the white one you can mentally string it back together and see that it was originally one continuous layer.

The name Van Gogh is perfectly fitting, isn't it?

Slab #3 - my first reaction is that this slab is dyed. There are plenty of orange-red minerals, and cranberry-red minerals, but aside from rubies, I can't think of any red-red minerals. It could be an iron-oxide that is making it red, but normally those have a bit more orange in them. The rock is made out of white/clear quartz but the cement between the quartz is what's giving it the red color. So it's either an iron-oxide cement or it's dyed.

Fun rocks, thank you!

Your description of how a rock feels when it does and does not scratch glass is exactly right. No doubt you've got yourself a quartzite then, yahoo!

How neat that you've worked in the space program - no wonder you see fossil spaceships and galaxies in these slabs!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #108)

posted by: azmom on 04.28.2013 at 12:01 am in Kitchens Forum

Hello Karin,
The GC brought me a piece of Moonlight sample after I posted the previous message. It bits in glass bottle easily. Moon-night was slippery, no matter how hard I tried I could not make a single scratch on glass. I also did vinegar and Ketchup test on the Moonlight sample of both polished and unpolished sides; it does not etch or stain.

We stumbled into the stone yard. After purchased the Moonlight, we learned from others that the place is a high end shop famous for exotic selections and high quality. I am happy for getting a nice quartzite slab, also for finding a trustworthy company for our future slab purchases.

Could you please tell us more about the three Quartzite slabs in the following photos? Such as how the color and patterns were formed. Each one of them shows us the beauty only mother nature could create.

Kaleidoscope: like a watercolor painting
 photo Pretty-1_zpsec232591.jpg

Mardi Gras, look at the fierce, violent beauty, so very van Gogh.

 photo pretty-2_zpsa33e1e2c.jpg

Revolution : Speechless, especially seeing it in person.
 photo pretty-3_zps58d5e62c.jpg

I spent a few years working on Space programs. Funny how our view could be influenced by our life experience even over a granite slab.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #107)

posted by: karin_mt on 04.27.2013 at 03:22 pm in Kitchens Forum

Hi Meyers,

I determined that the Brentwood is sandstone because you can still see the layering and bedding within the rock, and the layers a flat rather than twisted around and deformed. Horizontal layering is a diagnostic feature of a sedimentary rock. When a sandstone becomes quartzite the layering gets obliterated, or at the very least the layers get distorted. Some rocks are only partway along the metamorphic process and they still show faint layering. White Macabus quartzite is an example of this. In your case it looks like all the original layering is still intact. To be sure though, one needs to look at the quartz grains. In a sandstone, you can see individual sand grains. In a quartzite, the grains are fused together, hence the lower porosity. It's hard to see this with the naked eye, usually a hand lens is needed.

AZMom, that lower photo is great. I can see the space scene you describe! For me, it looks like an ancient ocean with all those animals zipping around, eating each other and whatnot. Of course my imagination is tainted by the fact that I know that those are marine fossils. Either way, the rock is a wonderful snapshot of a distant scene. How neat that rocks can preserve a moment for millennia.

On Moonight vs Moon Night, I would have guessed the rock types to be opposite from what you said they are. That just points out how impossible it is to tell them apart just by looking. The Moonlight is another example of a breccia rock that is made up of fragment that are glued together. I have seen plenty of marbles like that but not any quartzites. But that doesn't mean it can't happen, obviously!

That is going to be one dramatic and beautiful bathroom, nice going!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #106)

posted by: azmom on 04.27.2013 at 01:16 pm in Kitchens Forum

Hello karin,

We purchased the Moonlight. I did not test the slab because there was no sample available and I did not have my little glass bottle with me (thank you for the tips you shared with us). But stone yard sales manager, an employee there, our GC and fabricator all confirmed it is quartzite. In addition, the employee sent me a photo of her shower using the same Moonlight slabs. The shower is stunning. She said she loves the shower since it does not need much maintenance.

Here is the Moon night Marble:

 photo marble_zps385af7c0.jpg

The one with straps is Moonlight Quartzite.

 photo Slab_zpsd12c5583.jpg

My number one choice is a "Fusion" slab, yet it is too expensive. The Moon night is most closer slab to "Fusion" in the grey color we need. But I was too concerned about the number of long cracks throughout the slab.

When we saw the Moonlight, it is closer to Moon-night, but it does not have that "Fusion" look. But we were under schedule pressure and did not want to start all over again, after all, this is only for bathroom counter top. The Moonlight is more dramatic but with little blemishes. When running my hands over, it felt more smooth and harder. I thought it was a good marble slab before I learned that it is quartzite. Our GC likes the stone, he has spent fair amount of time with fabricator to template the slab. I hope the vanity counter top would turn out good.

Here is a dramatic. interest slab,

 photo spaceshuttle_zps29965608.jpg

As you mentioned earlier, it contains fossils. To me it looks like a photo of galaxy with moons, planets, and space shuttles flying around. This is one of the most amazing slabs I have ever seen.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #104)

posted by: karin_mt on 04.27.2013 at 11:15 am in Kitchens Forum

Hi Myers,

Hmm, these are interesting examples, thanks for sharing them. The Brentwood is a sandstone, not a quartzite, so that is why it is so porous. So, it's an un-metamorphosed version of quartzite. In other words if you take sandstone and put it through the metamorphic process (heat + pressure) you get quartzite. That process squeezes out the pore spaces and makes the rock denser, which is why a true quartzite is so strong. But this rock has not been through that process so it's a regular sandstone, a sedimentary rock.

If you can get a sealed sample to test, that would be key. But the high porosity may be a deal breaker, I'm not sure how effective and permanent it would be to seal it. I imagine the stone company can shed more light on that. You might also want to get the contact info of someone who has been living with that rock as a countertop for a few years to hear about how it holds up.

The second photo is a metamorphic rock, and it could be marble, or quartzite or something in the gneiss family (similar composition to granite). So do the scratch and etching tests on that one to rule out the possibility of it being marble. However if they won't give you a sample to test I'm not sure how to proceed. That rock looks a lot like a geologic map of the Appalachian mountains with their folded bands of rock. So I would be partial to that one, at least in terms of the visual.

I hope that helps!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #103)

posted by: meyersdvm on 04.27.2013 at 07:45 am in Kitchens Forum

My turn to ask about a stone. Thank you for all the advice and information, Karin. I have learned so much from your posts!

I am considering using a quartzite called Brentwood. It is quarried in the US by Semco Stone in Missouri.
http://www.semcodist.com/product.php?product=Brentwood Countertop

The stone is available in 6cm thick slabs which would keep me from having to laminate my edge. I have a sample (unsealed) that I am subjecting to torture this weekend. So far no etching, but it is porous and readily absorbs liquids. Staining TBD...
The photo below is a rough cut slab just out of the saw shop. The other stone in serious contention is a very light colored Prada Gold, but I have had little luck finding any details about staining, etc. for that one as well and cannot get a sample. Thanks for any insight.

Brentwood quartzite
image

Prada Gold granite

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #101)

posted by: karin_mt on 04.25.2013 at 11:45 am in Kitchens Forum

Hi Peke,

Natural rocks will often have cracks/fissures, so it's hard to make a blanket statement to avoid them all. Most cracks fill in with mineral cement, but that is not always strong. If a crack is open, that is something to be wary of.

You wouldn't want cracks in unsupported areas of the rock, like where it overhangs. Also watch for cracks near corners, edges or seams. But aside from that, a surface crack does not seem like a reason to be troubled. Really, if the rock is going to break it will likely be during fabrication, transport, or installation and in each of those cases it's the fabricator's problem, not yours. Once the slab is set in place there is not much stress acting on it. (aside from overhangs)

Laura,

It sounds like you have done your homework nicely and this rock is not limestone. My next guess is that it's a breccia made from pieces of a dark sandstone or an igneous rock like basalt. In either of those cases you will be safe from etching. Your slab is a nice departure from the usual stuff, so I'm looking forward to seeing it in action. Keep us posted!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #68)

posted by: karin_mt on 04.13.2013 at 11:26 pm in Kitchens Forum

I'm here - sorry!
Awesome rock. It's limestone with fossil nautiloids in it. Nautiloids are sort of squid-like creatures with tentacles and a chambered shell. The nautilus, with its familiar coiled shell is a modern cousin. This version has a straight shell. They swim in the ocean and they are predators.

For the most part, in this rock you are seeing them in side view. You can see the chambers in their shells, with a little curved line that separates each chamber. The little beastie lives (well, lived) in the outermost chamber.

Some of the fossils are ring-shaped and that's the same animal but you are looking at it head-on.

Nice sample! It would be a disaster in a kitchen though, being limestone.

Here is a link that might be useful: more about nautiloids

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #65)

posted by: Peke on 04.13.2013 at 01:35 am in Kitchens Forum

karen, I found this slab today. It was called fossil black.
What is the story behind it? Very interesting rock.
peke

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #64)

posted by: karin_mt on 04.08.2013 at 11:55 pm in Kitchens Forum

Hi Katy,

Genuine quartzite will perform very well in the kitchen and will be similar to granite in terms of durability and stain resistance.

I haven't really checked out the quartz colors much. I definitely like quartz countertops just as much as rock ones. In terms of durability I think they are all in the same range. There are slight pros and cons, but quartzite, granite and quartz are all good bets for kitchen performance.

Srosen, thanks for filling in the details there. I have not heard of using an acidic polishing compound on marble. I'll have to ponder that one for a bit.

Marion - if you are a Carrara gal, then go for it! No doubt it is a stunningly beautiful material. Enjoy!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #63)

posted by: ktemmaward on 04.08.2013 at 10:28 pm in Kitchens Forum

Hi Karin--I have spent the last hour+ reading through your very helpful posts. Thank you so much for your insights. I just wanted to clarify, if the Super White passes the scratch and acid tests, and I confirm it's a quartzite, how does that compare to granite (in terms of how you would want it to perform in the kitchen)?

Also, what are your thoughts on quartz, either the lagoon or lyra in terms of look and durability?

And I would love anyone else's input too.

Thanks in advance!
Katy

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #60)

posted by: srosen on 04.07.2013 at 03:13 pm in Kitchens Forum

Good point Karin,
I had always been told honed surfaces would be more porous than highly polished surfaces by my peers in the stone industry.
I was told polishing will close up the pores of the stone and the surface tension was increased making the surface less absorbing.
Granites are polished by abrasives ,pressure and heat.
When the stone starts to polish a being layer is formed thus making the stone
Very shines and less absorbent.
Well we ran some tests on Santa Cecilia ,Virginia mist and blue eyes.
Honed all these surfaces were absorbent .we sealed none of them and let liquids on for up to 2 hours.
Polished pieces also were absorbent .we didn't baby sit them so there was no way to tell which stained faster. The point is they all stained.
So while a polished surface may be less absorbent to some extent if you are buying an absorbent stone you will need to seal it well.
Marbles including limestones and travertines will show(depending on the stone) differences in absorption between honed and polished.
There is a scientific reason for that that however.
When calcareous stones get polished in the processing points the final polishing is done using an acidic(potassium oxalate ) polishing compound.
This creates a chemical reaction with the calcium in the stone forming calcium oxalate along with the beilby layer and theoretically the surface is less absorbent .
We will see if we can test some marbles as well.
Anyway I think the point is that consumers(and pros) should not take any info for granted and test everything.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #58)

posted by: karin_mt on 04.06.2013 at 07:31 pm in Kitchens Forum

Island,

I did some reading about White Ice. It's pretty much a true granite. I could not find any info on its porosity but I think the stone dealer should have that info for you.

There is a chart that I linked at the bottom of this post that lists the water absorption rate for a whole bunch of different granites. This ranges from 0.05% up to 0.5%. Sure enough Kashmir White is one of the more porous ones. I didn't see any trend that white ones are more porous. In general all of these "granites" (meaning all the igneous and metamorphic rocks that are called granite in the trade) are not very porous, but as with every stone, if you can bring a piece home you will learn how it behaves.

A few posts up Srosen commented that a slab is more porous when unpolished and less porous when polished. I don't think that is correct. Polishing alone (no sealer, no resin) does not change the properties of the rock. It just creates a very smooth and uniform surface, but it does not fill in any pore spaces within the rock. Sealer does change the porosity by filling in the voids.

I hope that helps!

Here is a link that might be useful: properties of various granites

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #57)

posted by: karin_mt on 04.06.2013 at 10:08 am in Kitchens Forum

Hi Lemon,

You're very sweet, thank you!

Hmm, Moon Night. That's a name I have not heard. I stared at your photo and googled around a bit. The answer is not clear. It does seem to be a synonym for Super White, which is a big red flag for marble rather than quartzite.

Scratching glass, yet a knife scratching it are contrary bits of evidence. When the knife scratched the stone, are you certain that the knife left a permanent indentation? Is it possible that the mark you saw was a trail of metal left by the knife? That will happen with a really hard rock. But if you rub the spot with your thumb and really look at it, you can tell who scratched who. Also, make sure you are doing the scratch tests with the rough, unpolished (unsealed) parts of the rock.

Testing it with a lemon or vinegar will reveal more answers. Can you get a sample?

As for seeing quartz in the rock - it's hard to visually distinguish between any of the white-ish minerals in a polished slab. Calcite is also white, as is feldspar. Quartz looks glassy and translucent and breaks with an irregular or sometimes a curving surface. Calcite is more cloudy and breaks into rhombus shapes with the planes intersecting at 120 and 60 degree angles. Feldspar has a porcelain-like luster to it and breaks on 90-degree planes.

The way minerals break is highly diagnostic yet is impossible to see on a polished surface where everything is equally flat. The edges of the rock hold some clues, but you have to know what to look for, and even then in some cases the edges are sawn flat. This is why geologists carry hammers - a freshly broken piece is your best friend. You think the slab yard folks would be cool with us showing up armed with hammers?

Anyway, in your photo you can see some tiny fracture lines going across the large white pieces. But they are not irregular like you'd expect with quartz and they are not at the angles that would be diagnostic for calcite either. Hmm.

The last clue is the overall texture of the rock. See how it's made of white pieces suspended in a grey background? That's called a breccia. Lots of marbles have this breccia texture, which comes from the rock breaking into bits as it undergoes stresses. I can't recall seeing a quartzite do this. So that would be one more clue toward marble.

So... I guess this is a long winded way of saying I don't know! If I *had* to guess I would lean toward marble. I'll look forward to hearing more about what you are able to find out. Thanks for sharing this mystery rock!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #56)

posted by: srosen on 04.06.2013 at 09:25 am in Kitchens Forum

Island,
Sorry for the delay in responding.
"Light granites tend to be more porous than dark granites"
That is such a broad statement these days with so many types of stones available.True granites tend to be more porous than mercantile granites a name devised to keep us all less confused. Mercantile granites are the stones sold as granite but geologically are different.Related in some ways but geologically different.
Feel any less confused!!
To add to this many stones today come in resined which makes them makes them resistant to stains and also fills fissure and natural pitting.
So it is extremely important to be an educated consumer and test stones for porosity, acid sensitivity and hardness.
To answer your question about white ice.
Stones should be tested on an individual basis.
While kashmir white is very porous.
I think you will find that white ice will show no signs of porosity as the stone is typically resined.
It comes from brazil but I am not sure if it is a true granite or not. Maybe Karin could look into that. I think it is a mercantile granite.
Anyway test a sample piece-I think you may be quite pleased.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #55)

posted by: LemonCitron on 04.05.2013 at 11:20 pm in Kitchens Forum

Hi Karin,

I have been following both rock threads for a while and I am absolutely charmed by you. Hoping you could help me out as well.

I found a slab called Moon Night (this also goes by Super White, White Princess, etc) which the stone yard calls a quartzite. I did the glass test and it scratched the glass. I also tried this with marble they had there and like you said, it did not scratch.

However, I was able to scratch the surface with a knife. What does that mean?

Also, I can see actual pieces of quartz in the slab. Does that mean anything? Or can marble have bits of quartz in it as well?

I was not able to do an acid test on it though.

Thanks again for a truly amazing reading experience. Everyone here has been so helpful. And entertaining!

Here is a pic of the slab in question.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #53)

posted by: karin_mt on 04.04.2013 at 07:44 pm in Kitchens Forum

GardenerCT,

Jet Mist has a strong following, while Absolute Black sometimes has some problems with the finish. People report etching, but that is not possible with Absolute Black, it is not soluble in household acids. The problem may be with the sealer.

Do you want a honed stone, or is that just the way you've seen it? There isn't really a difference in the durability of honed vs polished finishes in granite. A polished, dark stone takes diligent cleaning to keep it spot-free, but that would be less of an issue with a honed surface. Many people report that honed Jet Mist looks like soapstone.

But in terms of durability, I think you will be fine with either of these rocks, with any finish.

Island, it's true that you read about the white granites being more prone to staining. I'm not sure if that's because they are white and the stains show up more, or if there is another reason. But in any case, these will need careful sealing. I haven't heard of White Ice but maybe SRosen has. Was that one of the stones in a recent thread all about white granites? There were some stunners in there.

Welcome Ikeltz! I'm glad to see that you are such a good student. Marble is so classy. I admire all of you who can tolerate its bad habits. I am hoping for a marble top for our mantel and/or a buffet where I can appreciate it without cooking on or near it. But both of those projects are a year or more down the road. So until then I will live vicariously through other people's projects. Enjoy your shopping and testing! Be sure to keep us posted with your progress.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #46)

posted by: srosen on 03.30.2013 at 08:58 am in Kitchens Forum

La Jan,
I believe verde lichen is quartzite but lets see what karin says. From my perspective here what I think may have happened.
You tested the unsealed sample and found that it didnt etch and wasnt porous. (as it didnt absorb any liquids)
Your fabricator applied the first applications of sealer and more likely than not he may have known it wasnt porous. So he may have used small amounts and made sure he removed any leftover sealer from the surface of the stone.
Your stone was fine until after you applied more sealer to it.
Did you happen to do the water test for porosity prior to the application. You may have seen that the stone isnt porous.
If you applied the sealer to a very dense surface you must make sure that all the sealer residue is removed from the surface. Even if you leave a microscopic trace of sealer residue on the surface (sealer are impregnating and live below the surface)it can etch from acidic compounds.
We run into this issue often when folks try to seal stones like black absolute and other dense stones. They find stones that never etched before -etching!.
If you have a good relationship with your fabricator he may be able to help you remove the sealer or you can google up a stone refinisher in your area and he or she will be glad to service the stone and correct the issue.
As far as the cleaning of the pot-it probably left scuffs from the metal on the surface and some very fine abrasive compound will remove it. Even if they are light scratches they should be able to be removed.
Hope this helps!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #21)

posted by: karin_mt on 03.12.2013 at 10:44 am in Kitchens Forum

AAAAAGH!

That reminds me of grading freshman essays about rock forming processes. All the right words are in there, but they are combined in impossible ways.

"This is an amazing material. It is naturally strong, resists heat and is hard to stain.
Yes, this is right. We're off to a good start.

Quartzite is formed from sandstone and quartz together under a great deal of heat and pressure.
Not quite. Sandstone is made of quartz grains, so that's where the quartz comes from. No additional quartz is magically added to the rock. The part about a great deal of heat and pressure is right. Partial credit for that.

The empty grains of sandstone are filled with quartz.
What? Can you please explain what an empty grain of sandstone is? I think what they meant is that any empty spots in the rock disappear because the rock is compressed and the quartz grains re-grow to fill up any voids.

This process makes quartzite harder than quartz.
Hmm, not possible. Quartzite is made of quartz, right? So how can it be harder than quartz?

On the Mohs scale of hardness (1-10), with 10 the hardest, granite measures between 6 and 6.5; whereas quartzite measures around 7.
Yes, good job!

However, there is a chance for etching to occur on its surface."
Noooooo. This of course is only true if you are lying about quartzite and it is actually marble. Good catch Soibean!

Phew. That was fun! :)

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #18)

posted by: karin_mt on 03.06.2013 at 10:09 am in Kitchens Forum

Chicago,

Right, Super White Quartzite is likely not really quartzite. The reason I started posting about rocks on GW is because that stone is misrepresented as something it isn't. So I would assume Super White is marble unless your tests tell you otherwise.

Given that assumption, Super White is the same hardness as Danby and other marbles.

Yes, honed is better than polished for hiding etching.
Yes, sealer helps prevent staining but it is not absolute.

No idea about crayons or markers but you can experiment with that if you can bring home some samples.

Good luck!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #15)

posted by: karin_mt on 03.05.2013 at 11:24 pm in Kitchens Forum

Hi Chicago,

Here are some answers to your questions.

If i am understanding correctly Super White Quartzite is harder than marble, but still will etch.
No, not quite. First, let's abandon the name Super White, since sometimes that's marble and sometimes it's quartzite.
Quartzite is harder than marble and will not etch. Marble is soft and it etches.

Does this mean that you will get less chips around the sink area/edges than with marble?
Perhaps, but not always. Chipping is actually not necessarily related to hardness. Some very hard stones chip (see thread about Antartide quartzite).

Also do you know how Danby marble compares in hardness to Super white?
Again, the name introduces a lot of confusion to this question. Danby is the same hardness as Super White if the Super White is marble. But if the Super White is quartzite, then that would be harder than Danby.

Sorry that I don't have completely straight answers - the names of stones make it too confusing to take them literally. Best of luck with your research. You are smart to take your time and keep on reading.

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #9)

posted by: karin_mt on 03.01.2013 at 10:38 am in Kitchens Forum

Ginny,

Yes, yes and yes. You got everything right. Nice work! Garnets are (almost) always an indicator of a metamorphic rock like gneiss or schist, as opposed to an igneous rock like granite. But you can get garnets in sedimentary rocks as we have in our Wild Sea sandstone. That was one of the selling points of Wild Sea for me because you rarely see garnets like that.

The swirly, layery pattern in your rock and others like it is the other key feature of gneiss rather than granite. You are exactly right!

Schist is similar but with much more mica (either silvery muscovite or black biotite). Schist is not good as countertops because the micas are flaky and cannot be made smooth. It is suitable as flooring, siding, fireplaces or landscape rocks though.

As for limestone in the kitchen, it would be treated just like marble. A "hard" limestone is a myth. :) But having fossils in the kitchen would be cool, and is totally doable as long as you are OK with some etching and scratching. A geologist friend of mine has it. I don't know Jerusalem Limestone per se, but I think all the normal limestone properties would apply.

Love your salty animal friends there, they are quite the characters, aren't they?

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #8)

posted by: karin_mt on 03.01.2013 at 10:25 am in Kitchens Forum

Oh yay, rock questions! :)

EAM - sandstone. Great topic. You have done your homework and everything you wrote is exactly correct. The durability of a sandstone all comes down to how well it is cemented and what the cement is (and by cement I mean the natural minerals that are holding the sand grains together). For a sandstone to be useful in the kitchen you'd need silica cement. Calcite cement will suffer the same problems as limestone and marble.

In addition to silica cement, the rock also needs to be well-cemented. Some sandstones crumble apart in your hand and others are as dense and tough as granite. It depends how much the rock was compressed when it formed and how well the mineral-rich waters circulated through the sand to bring in the cementing agents. Some sandstones are a bit more like quartzite if they have been compressed a lot and they are very well stuck together. That is what you want for a kitchen application.

You can get sandstones that are commercially available as polished slabs. Wild Sea is a sandstone that we have in our kitchen. It is not very porous and it behaves like granite.

You can also get rough, non-polished sandstones as slabs with a rough-hewn, rustic look. A sandstone called Frontier Sandstone is locally available here as countertop slabs.

As for your local sandstone, I would go check it out. By handling it and doing some tests you'll be able to get a feel for how it will behave in the kitchen. Personally, I would not go for a porous sandstone in my kitchen. If you put water on it and the water gets sucked into the rock, I would shy away. I'd worry that it would be impossible to clean because what would happen when milk, wine, chicken broth and coffee get sucked into those pores? Of course you could seal the rock but if it's that porous to begin with it seems like an uphill battle.

So go have a look, snap some pics and let us know!

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #7)

posted by: Ginny20 on 02.28.2013 at 03:50 pm in Kitchens Forum

I realized I should show a you picture of my "gneiss" for verification.

 photo P4020348.jpg

This closeup shows the feldspar, which is a little pinker than it looks here. The bigger, dark roundish dots look like garnets to me.
 photo PA130410.jpg

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RE: Marble, quartzite and other rocks in the kitchen (Follow-Up #4)

posted by: EAM44 on 02.28.2013 at 09:30 am in Kitchens Forum

Karin - can you tell me a little about sandstone? I have tried to get info from others who have used it. No replies.

I am a scientist and have always wanted soapstone counters with runnels, a big sink, and a drying rack in my lab - I mean kitchen. I've noticed that one major soapstone counter vendor is also selling sandstone. I live right near the Berea formation... you see where I'm going with this... My fireplace is made of local sandstone. I would love to use a local sandstone for my kitchen counter.

Here's what I know:
1.) I've read it is a stone made from grains of sand cemented together by calcite, silica, or other minerals.

I don't know anything about the characteristics (how much matrix, what type of cement, pore size etc...) of my local sandstone that might make it more or less suitable for a counter material.

2.) I've read it can be friable and porous, and so, less than ideal for kitchen hygiene. But is this necessarily the case with all sandstones? My local sandstone? Each quarry shows stone that looks SO different from that in an adjacent quarry. There's tons of variability in the appearance of the stone. Might this mean there could be a variety that would make for a good counter choice? Can you educate me a little?

Thanks. E

Ohio Sandstone

Arizona Sandstone

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Marble, quartzite and other rocks in the kitchen

posted by: karin_mt on 02.27.2013 at 11:35 pm in Kitchens Forum

The thread about Super White, quartzite, marble and all things stone has run its course up to the 150 post limit. Who knew we'd all have so much fun with that topic? So we'll start a new one here. I guess the first thread was Rocks 101, so this one must be Rocks 102.

I'll reiterate some key points here:

Quartzite and marble are hopelessly (deliberately?) mixed up in the decorative stone industry. My point, aside from just loving rocks, is to help folks learn how to tell the difference between the two so you are not at the mercy of a sales rep when a multi-thousand dollar purchase hangs in the balance.

Quartzite is much harder than marble and will not etch when exposed to acids. You can tell the difference between quartzite and marble by doing the scratch test.

Take a glass bottle with you when you go stone shopping. Find a rough, sharp edge of the stone. Drag the glass over the edge of the stone. Press pretty hard. Try to scratch the glass with the stone.

Quartzite will bite right into the glass and will leave a big scratch mark.
Any feldspar will do the same. (Granites are made mostly of feldspar)

Calcite and dolomite (that's what marble and limestone are made of) will not scratch. In fact you will be able to feel in your hand that the rock won't bite into the glass. It feels slippery, no matter how hard you press.

PS - don't press so hard that you risk breaking the glass bottle. You shouldn't need to press that hard!

That aside, we can talk about other rocks too. Coal, pumice, sparkly crystals, you name it. OK, I guess we're mostly interested in kitchen rocks. :)

Here is a link that might be useful: the lowdown on Super White (aka Rocks 101)

This post was edited by karin_mt on Wed, Feb 27, 13 at 23:41

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RE: The lowdown on Super White (Follow-Up #103)

posted by: jterrilynn on 01.08.2013 at 09:49 am in Kitchens Forum

Hi Karin, thank you very much! You have inspired me to learn a bit more. Of course this is all elementary to you but I thought I would share with others.

Here is a link that might be useful: knowing our stone counter top - Metamorphism and Metamorphic Rocks

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RE: The lowdown on Super White (Follow-Up #102)

posted by: karin_mt on 01.08.2013 at 12:12 am in Kitchens Forum

What a nice story of a travel-inspired kitchen, I like that.

Attached is an image that points out a few features of your rock. It's gneiss, which is a metamorphic rock. It's not quartzite because it only has a little bit of quartz in it. The white veins are pure quartz. They formed when small amounts of the rock melted while the whole rock was undergoing metamorphism. Metamorphism means deep burial, intense squeezing, and temps not quite hot enough to melt the rock, but still hot enough to cause changes in the rock. For example, the heating and compression of the rock caused all the minerals to align into bands of color. That is the hallmark of gneiss.

In one spot you can see the rock is actually bent into a folded u-shape. That is another sign of the compression and torture the rock went through while in a heated, plastic state.

The orange/pink/apricot color mineral is feldspar. That color is diagnostic of potassium-rich feldspar. That's a common mineral in both granite and gneiss.

The lower photo shows an area where the rock was fractured and water traveled through the fracture, carrying other minerals and altering the chemistry. That's why only that area has the green color.

It's a neat rock with a lot of interesting features that tell us a bit about its story. Thanks for sharing it with us!

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RE: The lowdown on Super White (Follow-Up #99)

posted by: Terzen on 01.07.2013 at 02:26 am in Kitchens Forum

Karin mt,

I found an earlier post and would appreciate your thoughts about quartzite etching:

eeeek...etching on new quartzite counter


HI all
Our hearts have been set on Quartzite Bianca (aka Luce de luna, Aspen White) but I just found out from our fabricator who called the Marble Institute of America, the reason some quartzites are etching is because... the supplier applied resin to it prior to shipping it to the distributor, which makes it highly susceptible to etching. They apply resin or sealer to it before shipping to "enhance" certain physical characteristics of the stone. Either they don't know or care about how they also make it highly susceptible to etching!!

I also found out from the Marble Institute of America that using cleaners that contain hydrofluoric acid will etch quartzite (as in, cleaning your stainless steel sink and some gets on the countertops).

So... ask the place where you bought your quartzite if the supplier (company that deals with the quarry) applied resin or sealer. If so, that's what's making your countertop etch when say lemon juice gets on it. At least according to my fabricator, there is nothing that can be done after the fact because the resin (or sealer--not to be confused with the sealer your fabricator applies for stain protection) has impregnated the pores and no amount of polishing can reverse it.

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RE: The lowdown on Super White (Follow-Up #70)

posted by: karin_mt on 12.14.2012 at 02:28 pm in Kitchens Forum

Hi Derek,

Thanks for being such a good sport. I know you are only reporting how it is! :)

On Absolute Black and the use of "granite."
I understand that the word granite is applied across many rock types. I have no problem with that. From what I've seen, granite is meant to mean any igneous rock, whether black, white or otherwise. Granite also is the name used for most metamorphic rocks that contain a similar mixture of minerals. Most of these metamorphic rocks are called gneiss ("nice") but they have the similar minerals and almost the same texture so it really doesn't matter. In these cases there is no difference for the consumer; it is purely academic, so I am happy to leave that as it is.

As an aside, Absolute Black did not form from silica or black sand fusing together. That is actually way off, I'm sorry to say! Absolute Black is formed from liquid magma that pooled underground but did not erupt. It's what geologists call an intrusive igneous rock: it "intruded" as a liquid into the earth's crust and then cooled in place. This is the same way many of the kitcheny granite-like rocks form. The colors are just different variations of the minerals but for kitchen purposes it doesn't matter because they all have similar properties.

Brazilian vs Italian marbles
Yes, I agree they are not different minerals. But since they are the same minerals, they also share the same (or very similar) properties. Sure, the specs will vary within a range. But for kitchen purposes they are all marble and they all need to be kept in the same category for consumers. There is a slight difference between calcite and dolomite, but not enough to make a difference for the consumer. Either one will scratch and etch.

If I were selling someone a countertop (which I think would be fun because I have abundant enthusiasm for them all!) I would point to a slab of Super White/Classic White and say: "This is marble. It is harder than soapstone but much softer than granite. It will etch from contact with household acids. But it is stunningly beautiful. If you love it and you understand the risks, you should buy it and you will come to embrace it in your home. But know that it is not like granite so that you have the correct expectations. We want everyone to be in love with their choices, both for the looks and the utility."

Then I would show them a REAL quartzite and I would say: "This is quartzite. It looks like beautiful marble but it is way stronger. It's harder than granite! It won't etch. It's awesome. But it costs one million dollars per square foot. (insert correct price here). But it's the best of both worlds so it costs more. It also costs more because it's a PITA to fabricate because it is so darned hard. There is much misinformation in the industry about quartzite, but this is the real stuff. I will show you the difference with two rocks that look similar (marble and quartzite) but perform dramatically different." (perform scratch test, show results of acid tests).

Then I would show them granites: "These rocks are all called granite. They come in many different colors and patterns. But they will all wear similarly. They are made of nearly the same thing despite their different look. If you want to learn more about what makes them different colors, then I can find out more for you." (At that point come to GW and ask and I will tell you!)

So that's my recommendation. I think this is clear enough so that any consumer could understand it. Plus, soon you will be viewed as heroes by your customers since you are giving them the straight dope. As you can see by the many comments here, customers are frustrated with the lack of clear information.

I hope that helps!

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RE: The lowdown on Super White (Follow-Up #69)

posted by: marble_com on 12.14.2012 at 10:27 am in Kitchens Forum

Hi Karen,

I'm simply trying to provide some helpful insight into how the granite fabrication industry generally behaves. I know it's not right, but it's just the way it is. Just to give you an example, 99% of the time a salesmen does not know Absolute Black is not really granite, and they say it's granite. It is a common and accepted practice by many people in the stone industry to use the name "Absolute Black Granite". Geologists would disagree that Absolute Black Granite and most other black granite are not granite at all! From what I understand, it is made of silica, black sand fused under extreme heat to become a form of glass.

If you ready my previous post carefully, I did not say that Brazilian vs. Italian marble have different "minerals" or anything like that, I simply said that they have a little different specs (technical information) such as absorption by weight, density, compressive strength, abrasion resistance hardness. This technical information are tested and checked by the quarry and come as a material data sheet when a fabricator direct imports the slabs.

Lastly, maybe I didn't understand you correctly, but I thought you had said in your original post that there is a difference between dolomitic calcite marble vs. calcite marble, which probably creates some level of difference between care and maintenance of the stone, and perhaps the technical specifications. I was simply making the correlation that this sounds like what my import manager said about brazilian vs. italian marble.

It is great to talk to a geologist and I hope to learn new things from you to be a better person in the stone industry! :) I know I already have!

This post was edited by marble_com on Fri, Dec 14, 12 at 10:29

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RE: The lowdown on Super White (Follow-Up #68)

posted by: soibean on 12.14.2012 at 07:45 am in Kitchens Forum

Bless you, Karen. We are so appreciative of your expertise and assistance. It is so hard to get good information from stone yards and fabricators, and very often they contradict each other. I try to ask specific questions, but get answers like "it's between marble and granite," or, "all white stones will stain." Yes, but is this quartzite or not? Will it etch or not? I can't tell you how many people won't even distinguish between staining and etching when you ask. And they won't give samples either. Your glass scratch test has been invaluable for me, and for others as well, I'm sure. It's nice to know what you're getting before you plunk down thousands of dollars. Keep up the good work!!

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RE: The lowdown on Super White (Follow-Up #66)

posted by: karin_mt on 12.13.2012 at 09:00 pm in Kitchens Forum

Halfwaythere - (your name makes me curious what you are halfway toward?)

I can tell you 100% that your rock is not granite, that part is certain. It is only one of two things: marble or quartzite. I don't have a hunch one way or the other. The glass test will tell you unequivocally which one. Now, the stoneyard may call it granite but they are just plain wrong! :) But that's OK, it's more important that *you* know what it is. Good luck with the glass test and I hope it turns out to be quartzite.

As for the little faults in there, yes they are or were planes of weakness. But they have healed up by filling in with minerals. Of course it's hard to say just how strongly they are bound together. If it were my kitchen I would not put those in a place where they are cantilevered out, but aside from that I bet they are fine. The stressful part will be the fabrication and the installation and if it lives through that you'll be fine. And if it doesn't live through that, well that is the responsibility of the fabricator, so you are covered. My hunch is that it will be fine. I don't think that weak rocks make it very far in the stone trade since fabricators lose money on them.

Good luck and please report back! My fingers are crossed that it works out for you. I know how exciting it is when you find just the right thing and you realllly want it to work out. :)

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RE: The lowdown on Super White (Follow-Up #67)

posted by: karin_mt on 12.13.2012 at 09:31 pm in Kitchens Forum

Derek,

Thanks for your post. I am going to sound mean here, and I don't intend that. But what you are saying is not correct. Perhaps you are trying to make it easier for customers, but IMHO you are making it much, much worse by saying something that is simply not true.

There is no such thing as a marble that is halfway between marble and granite. That's just wrong. Marble is marble. The minerals don't behave differently if they are from Brazil or Italy. Marble can be made of calcite (hardness = 3) or dolomite (harness = 3.5). In either case that is very soft, softer than glass, softer than knives, softer than pots and pans. It is also soluble in acid, period.

For rocks like Super White/Classic White and others that are similar, they are either marble or they are quartzite. They aren't granite! I think you would help out the industry tremendously if you dropped that term altogether.

Now, the question that keeps coming up: is it marble or is it quartzite? Well, you have the tools to determine which it is. So I would encourage you to go ahead and do that and then tell your customers exactly what it is. Customers are smarter than you give them credit for and honestly telling someone about Brazilian marble compared to Italian marble is a whole lot more confusing than just saying it's marble or it's quartzite.

I agree that in the long run we want customers to love their kitchens and to be thrilled with all of their choices. I think the easiest way to assure that is to explain carefully and factually so that folks really do understand which rock they are buying. As you can see I have taken this on as a public service mission so pardon my strong feelings here! I really don't mean to be obnoxious, I just love rocks! :)

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RE: The lowdown on Super White (Follow-Up #61)

posted by: halfwaythere on 12.13.2012 at 03:24 am in Kitchens Forum

karin_mt wrote...And if you have questions about the real identity or geologic history of your countertop, I may be able to shed some light!
Karin

Jackpot!!! Finding this thread is so timely for me as I've found what I believe to be a quartzite that I love and I am going to do the bottle test. I am meeting with my fabricator tomorrow at the stone yard to get his opinion too. Karin I want to thank you for your informative posts here. You rock, you are a gem, pun intended! I've been lurking here for a while, really drooling over the quartzite here on GW. I think I've found a beauty, but the stone yard is insisting it's a granite slab called White Macauba. I've seen pics of installed White Macauba quartzite here on GW and it clearly is not. My google searches lead me to believe its is a quartzite called Gold Macauba or Giallo Macauba. He insists it's not quartzite. What do you think? I know you said it's hard to tell from a photo but can you make an educated guess? If it passes the bottle and acid test you recommended I will be buying it tomorrow. I cook every day and am a very messy cook at that, so marble is out for me. I love, love, love the flow of quartzite but have been unable to find a suitable color as my cabinets are warm tones. I think this one fits the bill. Also, those fracture lines (which I adore), are they what you refer to as "planes of potential weakness"? Not that anyone will be jumping on it. What potential problem do you see in general kitchen use with a potential plane of weakness. Thanks for your input. You are very generous with your knowledge.

This post was edited by halfwaythere on Thu, Dec 13, 12 at 3:35

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RE: The lowdown on Super White (Follow-Up #64)

posted by: marble_com on 12.13.2012 at 10:08 am in Kitchens Forum

Just something to add for OP -- you are absolutely correct that the natural stone industry (fabricators & wholesalers) often times do not correctly classify the stones geologically as they should be. While I don't have the knowledge of geologist, I suspect that Super White is what my import manager calls Brazilian Marble. Brazilian Marble has different specs than Italian Marble. It is suitable for kitchen countertops (as opposed to the more calcite-based Italian Marble) but there's more maintenance involved since color is very light and material not as dense as normal granite. For example, we classify our stone called Classic White as this "stronger" marble. We say it's not a granite, not a quartzite, and not a regular marble. Kind of in-between granite and marble, is what we say (well at least I know I do). We have to explain it in layman's terms like this, so it's easy for clients to understand. These very light marble-looking granite-like stones are HOT on the market right now for kitchen countertop application. EVERYONE wants a "white granite" and desperately look for it, although in reality (with correct classification) it does not really exist. However, there is confusion in the industry because of all this, as some fabricators do classify colors such as the Classic White I've shown as a "granite" because it has pretty similar characteristics. Because of this, sometimes customers get countertops installed with this material without knowing the real maintenance involved (thinking it's like a regular granite) and then are unhappy when it stains or chips or something. I hope this provided some helpful insight.

Here is a link that might be useful: Classic White

This post was edited by marble_com on Thu, Dec 13, 12 at 10:11

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RE: The lowdown on Super White (Follow-Up #37)

posted by: karin_mt on 10.29.2012 at 10:31 am in Kitchens Forum

Yay, more rocks!

Madeline - I think your Danby is OK. I suppose if it worries you you could add more supports underneath, but for now you are safe, phew!

Colorfast - I sure hope there is some legit Super White somewhere. I don't like the notion of deliberately using the wrong rock type to describe the stone. And you are exactly right about the added fabrication time/effort. That will be a hallmark of working with any quartzite.

Your Dynamic Blue is a really interesting rock. I know you said I don't need to analyze it but I will anyway. :) It is a metamorphic rock called gneiss (pronounced "nice"). So when people look at your fabulous countertop and exclaim, "Nice!" they are exactly correct. :) The raspberry colored bits are garnet. Garnet is a diagnostic mineral. It only forms in certain conditions (extraordinarily high pressures associated with deep burial) so that tells you that the rock was formed under intense metamorphism. As a result of the high pressure, all the mineral grains aligned themselves in a similar direction. The other minerals in the rock are similar to granite: feldspars, quartz, horneblende and some micas (muscovite and/or biotite). Gniess is strong and robust - ideal for kitchen use. The reason it is classified as a granite is because it is similar in composition and is similarly tough.

Soilbean,

Now that is a really white granite - the whitest one I've seen. This is pretty close to an actual granite. The composition is 90% felspar and in this case the faldspar is white. The black bits are biotite and there is a tiny bit of quartz which is a glassy, clearish grey color in this rock. I can't see any reason why it would be prone to staining - it ought to behave just like any other true granite. BUT, I can only say that from a theoretical point of view - you definitely need to test it out. The rock yard just has to give you a sample, no way around that. That's like a car dealer expecting you to buy a new car without allowing a test drive.

You can think of this rock as the white version of rocks like Blue Pearl. It's almost the exact same rock except the feldspar is white in this case and in Blue Pearl the feldspar is black. This stone is an ideal substitute for white marbles because the effect is similar but the performance ought to be better.

Hope that helps!

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RE: The lowdown on Super White (Follow-Up #36)

posted by: soibean on 10.29.2012 at 08:53 am in Kitchens Forum

Karin,

Thanks so much for all of the great information. This is an incredibly helpful thread! I was wondering if you have any thoughts about lighter/whiter granites. Are they more likely to stain? I am looking at a white-based granite called white ice, and I can't get a sample to test at home. I'm worried that it will stain and I have no idea how to find out before purchasing. Any ideas?

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RE: The lowdown on Super White (Follow-Up #35)

posted by: colorfast on 10.29.2012 at 12:03 am in Kitchens Forum

Karin,
I too am loving this thread.

I wanted to share that I do think Superwhite (which goes by several names) is perhaps more than one stone. Here in the Pacific Northwest, I found it as Moon Night, and had a bid placed with our fabricator. They charged more for it than the other granites including the standard Steel Gray or the Dynamic Blue we chose. They said it was because Moon Night was a quartzite and was much harder physically and required more labor.

Here's my granite, Dynamic Blue. I don't want you to feel you need to analyze it, just enjoy!

Dynamic Blue

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RE: The lowdown on Super White (Follow-Up #34)

posted by: Madeline616 on 10.28.2012 at 10:48 pm in Kitchens Forum

Thanks, Karin!

The slab is 3cm, and the streaks are parallel to the island. It looks to still be perfectly level and in perfect condition.

It's such a crazy thing...I didn't think anything of it when he started pressing down, but sure enough, the slab flexed the slightest bit...

I really appreciate your taking the time to offer some insights :) :)

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RE: The lowdown on Super White (Follow-Up #33)

posted by: karin_mt on 10.28.2012 at 08:11 pm in Kitchens Forum

Madeline-

Ahh, Vermont stone. I think it would be neat to have a US stone, which few of them seem to be.

How thick is the slab?

Honestly, I'm having a hard time imagining the stone visibly flexing, but not showing any cracking or other signs. Rocks are not elastic at room temperature. They can't bend without breaking. Is that edge still perfectly level? That's worth checking out.

When you stand back and view the rock, does it have a directional grain? As in, do most of the streaks point in a similar direction?

And if so, is this direction parallel to the edge of the countertop?

Marble is a strong rock (meaning resistance to breaking not resistance to scratching). But any metamorphic rock is weaker along the grain, just like wood.

So let us know the answer to these questions.

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RE: The lowdown on Super White (Follow-Up #32)

posted by: karin_mt on 10.28.2012 at 08:03 pm in Kitchens Forum

Dr Beanie, you sound like you were very thorough in your shopping, good for you! Sounds like it most likely is quartzite after all. I imagine you would know by now if it wasn't.

So, assuming it is quartzite, Blue Louise began life as a sandstone that was made of mostly quartz, but had other ingredients in it too. Probably it originally had some clays in it. That sandstone got buried deeply, then more deeply and was subjected to enormous heat and pressure, as you can imagine would happen if something was kilometers down within the Earth's crust. The pressure took the original horizontal layering and folded it in on itself. The heat allowed the rock to be pliable and the whole thing was sort of taffy-like. Just looking at the rock you can imagine taffy, right?

Meanwhile the rock was hot enough for the minerals to reorganize themselves, but not hot enough to really melt. The sand grains recrystallized so that became interlocking, rather than individual rounded grains like in the original sandstone. This interlocking nature is what makes quartzite so tough - each grain is perfectly interlocked with all its neighbors.

The other colors come from other ingredients in the rock. If the rock has a slight silvery sparkle to it, that's muscovite, which is what you get if you metamorphose clay. The green and the reddish orange come from iron, magnesium and other elements mixed with silica. Hard to say exactly what minerals those are, but you get the idea. Cool rock!

Next questions:

Netting on the back of slabs.
I wouldn't worry about this. It's good insurance for the fabricator while they are moving the slab around and cutting it. I think the netting comes off as part of the fabrication process. Anyway, no need to worry.

Durability of granites
Granite and all the other igneous rocks are similarly bombproof. At least, this is true from the geologic point of view. Those rocks are generally free of weak planes and are made of minerals that are all (or mostly) harder than glass and steel and are not affected by household acids. They also have an interlocking texture, meaning each mineral grain is thoroughly embracing all its neighbors. That means there is almost no pore space in the rock - no place for liquids to go or for stains to form. So I'd be happy with any granite or so-called granite in a kitchen. Now, that said, I have zero experience field testing these in a kitchen. I suppose it's possible that certain stones could be prone to stains in an unusual way. But as a category granite and igneous rocks are good bets for kitchen durability.

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RE: The lowdown on Super White (Follow-Up #31)

posted by: Madeline616 on 10.28.2012 at 07:28 pm in Kitchens Forum

Karin...I can't believe we have a geologist in the forum. This is like the cooking version of Barefoot Contessa walking into my kitchen.

I can't resist. I have to ask you a question that's been bothering the OCD side of me for a few weeks. If you have a second to shoot me a super quick response it'd be greatly appreciated!

I have Vermont Danby. The island has an overhang (with small corbels) where we sit on bar stools--so there's about 12" of marble that hangs over with no corbel under it. My fabricator made me promise never to sit on it, for fear of it snapping off.

Anyway...a few weeks ago, my husband was opening a childproof cap on a medicine bottle (where you press down really hard and turn). The bottle was, of course, on the marble overhang.

I was standing like 3 feet away, and I actually *saw* the marble bend!! I screamed and he released the bottle and shot his hands up in the air like a pinched criminal.

It only bent a tiny bit, and there were no cracks or damage, but nonetheless, I've been wondering ever since whether the marble might be "weakened" in that area, or whether the very fact that it "flexed" means it those little molecules are arranged to give it a little wiggle room and it's no worse for the wear.

I was recently wishing I could pose this question to a real marble expert (as in geologist, not slab salesman)...anyway, thanks :)

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RE: The lowdown on Super White (Follow-Up #29)

posted by: drbeanie2000 on 10.28.2012 at 06:26 pm in Kitchens Forum

Oh, I think Blue Louise is a quartzite! It did have netting on the back.

One fabricator - not the one we went with! - said it was fragile because of the cracks, fissures, whatever that usually indicate rust in them. They said this with a great deal of smugness, explaining why they didn't have any and wouldn't carry it if they could.

We did have 4 different samples of our rock (our actual slab, it was evident), some with more white than others. I had already heard something of these issues with white stones, even white veining in not-altogether-white stones, and how they might be calcium and subject to etching. I'm a sloppy cook, and we use lots of tomatoes, lemons, limes, vinegar, etc., so I poured whatever I could think of on those samples and paid careful attention to the white bits. I left half a lime on one for days. Nothing made the slightest impact on the samples. I admit, I had not heard of the glass test.

So I WAS confident it was quartzite and that it would be fine with whatever we spilled on it. They did say it was a PITA to cut. I have to say, though, that when the backsplash piece was somehow a little off and they were trying to get it between the range top and the hood, and started whacking it into place with what sounded like a great deal of vigor, I had to leave!

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RE: The lowdown on Super White (Follow-Up #28)

posted by: karin_mt on 10.28.2012 at 05:07 pm in Kitchens Forum

Cloud Swift,

That is another awesome looking rock, wow!

So cross-bedding... cross bedding is only visible in sedimentary rocks. When a rock gets metamorphosed, it erases the cross bedding. The swirly, taffy-like pattern in your slab and in other metamorphic rocks (quartzite and marble being two examples) is called foliation. It's a result of the rock being compressed to the extreme, which squeezes up the original layering in the rock and squishes it into ribbon-like patterns. Foliation is what makes metamorphic rocks mesmerizing, as it creates the swirls and bands of color.

The link below has a photo of cross bedding out in the real world.

Lastly - is it possible that Super White is actually more than one rock? Yes, that is very possible and perhaps likely.

OK, more later. Back to the garden now!

Here is a link that might be useful: Navajo Sandstone

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RE: The lowdown on Super White (Follow-Up #27)

posted by: karin_mt on 10.28.2012 at 04:51 pm in Kitchens Forum

Dr. Beanie,

That Blue Louise is amazing! Is it quartzite... million dollar question. Ok, maybe ten thousand dollar question. But Cloud Swift is on the right track.

If you totally trust your fabricator, they will know the difference the moment the saw hits the stone. Quartzite is even harder than granite (albeit not by much) and as Cloud said they will have to go slow and they will probably use up more blades in the process. Marble cuts easily.

If you aren't able to ask your fabricator, your next option, and frankly your best option anyway, is to do the glass-scratch test described above. Do you have a leftover piece from your project? Or can you get one from the stone yard? The glass-scratch is basically foolproof.

So try those things. I can't tell the difference between quartzite and marble from a photo. Much of the time I can't tell by looking at a polished slab either. You need a rough, broken edge to really see the character of the rock. (That said, my gut feeling on the Blue Louise is that it is a quartzite, but don't take my word for it!)

A few other things about telling quartzite from marble:

Some rocks have beautiful white veins running through them. Often those are calcite while the rest of the rock can be something else. So in those cases you could have one area of the rock that is soft and etchable while the rest is bulletproof. This can be true for any rock. So if possible, try the glass scratch on both the main body of the rock and also the veins.

There is also an acid test for calcite in rocks. But I doubt that any stone yard will let you dribble acid on their slabs! So you'd have to do this with a piece you bring home. But you can place a drop of white vinegar on the rock and see what happens. If little bubbles form, that is the vinegar dissolving the rock. Try that on a few places, especially white veins. If the first round of tests yield no bubbles, you are not in the clear yet. Try it all over again, but rough up the stone first. Take a nail, the tip of a knife blade, or some such, and make some nice scratches in the surface. (Note if you can't make a scratch in the surface, you probably don't have marble, as quartz and feldspar are harder than steel.) Leave the dusty stuff you've made while scratching. Put a few drops of acid on it and watch very closely. This is the test for dolomite. Calcite bubbles right away. Dolomite bubbles only if you scratch up the spot first. And any sealer could get in the way of this so try it on the edge if possible.

I really encourage any of you to try these tests, just for kicks. Even if you aren't worried about your stone, it is interesting to try the glass scratch and see how it does, just for your own knowledge. I am also imagining that we will start a trend of saavy shoppers who will bring glass bottles along while shopping and will be scratching and sniffing all around the slab yard....

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RE: The lowdown on Super White (Follow-Up #26)

posted by: donaleen on 10.28.2012 at 02:06 pm in Kitchens Forum

Thanks for the compliment, Island. I think there are three things that "make" my kitchen: lighting, color, and all the eclectic furniture in it.

I knew so little about stone and I was very nervous about selecting the granite and whether I would even like it. I only got to see it in the stone yard, propped on its side, in harsh lighting. The day before it came, I was totally freaking out because if it was wrong, it would be a very expensive and hard to rectify mistake. I threatened to put a table cloth over the whole island if I hated it.

I was also really unsure about how sturdy/durable it would be. I feel lucky I DO really like it and that it is trouble free. I think we are all hungry for the knowledge Karin has about stone.

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RE: The lowdown on Super White (Follow-Up #24)

posted by: cloud_swift on 10.28.2012 at 01:40 pm in Kitchens Forum

I don't understand how to identify a stone pattern that shows cross bedding. Is it something where the grain isn't in straight strata and it wiggles around? Our Azul do Mar is quartzite so it would have started out as sandstone then metamorphized by heat and pressure. Does it show cross bedding?

Photobucket

Photobucket

I'm fairly sure that quartzite is correct for this stone - our fabricator told us that it was taking longer to fabricate because they had to run the machine slower because of its hardness and we saw them dealing with that drilling the faucet holes on site.

I'm a bit confused about super white still because some folks that have it say theirs doesn't etch and that it is quite hard. Perhaps more than one stone is being sold under that name (as happens for absolute black).

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RE: The lowdown on Super White (Follow-Up #23)

posted by: drbeanie2000 on 10.28.2012 at 12:07 pm in Kitchens Forum

Ooh - me me me!!

What was called "Blue Louise" or "Van Gogh" and supposedly quartzite...

Close up:

IMG-20121026-00014

Close up:
IMG-20121026-00015

Full slab:

photo (1)

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RE: The lowdown on Super White (Follow-Up #22)

posted by: karin_mt on 10.28.2012 at 12:32 am in Kitchens Forum

Donaleen, you are a fellow Montanan, yay! Thanks for the additional photos. As far as I can tell in the photo, I'll stick with my original guesstimate.

The black is not obsidian, I'm sorry to say. Obsidian is a volcanic rock (and a very cool one at that!) which forms on the surface of the earth, so you can't find it in a granite which forms underground. But those black grains do look like obsidian. If you really want to know what they are, you'll need to study the shape of the grains. Hornblende is shaped like long, skinny rectangles. Biotite is actually little flakes, but often the flakes are stacked together. But occasionally you'll see one of the flakes on edge, about the width of a pencil line. It's also possible that both hornblende and biotite might be present too.

I'm glad that folks are finding this info is interesting and useful!

Ah, I figured the question would come up about which stone we picked. Well, hold onto your hats for this bit of heresy: our countertops will be gasp laminate! But don't worry, it's not one of those laminates that tries to imitate stone because that would clearly drive me crazy. And we are using stone for the windowsill and the bar top. Our kitchen will be sleek and modern (we hope) and most stones are just too busy for our small space. (more heresy, I know!) Quartz products would have been perfect but this is a moderately-priced resurfacing rather than a full fledged overhaul, and we just could not swing the price. Plus the countertop will be a snazzy silver which we are excited about. More about that in another thread.

The stone we're using for the windowsill and the bar top is Wild Sea. The windowsill has already been installed. It's over the sink and gets wet frequently so I've always wanted stone there. Now that the windowsill is in (and I love it daily) we agreed that more Wild Sea would be good as another accent.

Wild Sea is a quartz sandstone. It has cross-bedding, which is a swoopy pattern that forms when sand grains are deposited by flowing water. The cross beds are also what gives Wild Sea its name because they look like waves. I love rocks that have visible evidence of how they were formed. The cross-beds in Wild Sea do just that. You can even tell which direction the water was flowing when the rock was deposited. The pieces we're using for the bar top have particularly expressive cross-bedding and they will look so cool in that spot. Every visitor will get a mandatory geology lesson about the rock!

I have a bunch of questions about our kitchen which I will save for another thread. Just about all the decisions are made, but we've had a few stumbling blocks that I have questions about.

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RE: The lowdown on Super White (Follow-Up #20)

posted by: marti8a on 10.27.2012 at 05:28 pm in Kitchens Forum

That was interesting. I wish I had known more about the different qualities before picking mine. I did a search yesterday on sealers and Kashmir Gold and found a lot of sources that said not to even consider it in the kitchen because it stains so badly. Eeek.

But I'm curious. Which stone did you pick?

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RE: The lowdown on Super White (Follow-Up #19)

posted by: donaleen on 10.27.2012 at 03:32 pm in Kitchens Forum

Karin, thanks so much for your thoughts and for admiring my kitchen. I think Island is right that it is usually sold as seafoam green granite.

I looked up seafoam green and the photos look like my counter top. However, it did NOT have a netting on the back. The link is for that info. It was mid priced and we actually got a discount since it was the last slab they had.

The black in it looks like obsidian to me. (I live in Portland and we have lots of lava flow rock about). It is a shiny black. And yes, I think it has quartz in it, too.

I love what you have to say. I like learning about geology.

BTW, I was born and raised in Eastern Montana.

Here is a link that might be useful: seafoam green granite

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RE: The lowdown on Super White (Follow-Up #18)

posted by: karin_mt on 10.27.2012 at 03:17 pm in Kitchens Forum

I am also wondering about Macabus quartzite. I can't tell without looking at it, but I can tell you how to easily find out for yourself if you see a piece. Take a glass bottle with you when you go stone shopping. Find a rough, sharp edge of the stone. Drag the glass over the edge of the stone. Press pretty hard. Try to scratch the glass with the stone.

Quartzite will bite right into the glass and will leave a big scratch mark.
Any feldspar will do the same.

Calcite and dolomite will not scratch. In fact you will be able to feel in your hand that the rock won't bite into the glass. It feels slippery, no matter how hard you press.

PS - don't press so hard that you risk breaking the glass bottle. You shouldn't need to press that hard!

So - next person to see the Macabus quartzite or any other quartzite, please try this and report back!

Island - agreed that a bathroom could also spell trouble for marble. A bathroom might be a little friendlier in terms of acids and metal objects. But you make an excellent point.

Donaleen, what a beautiful kitchen you have! Your granite looks pretty close to actual granite, but it's a little hard to tell in the picture. I can say for sure that it is an igneous rock (formed from a liquid magma underground). Each grain is a different mineral. All the minerals together make up the rock. Some rocks are made up of bits of other rocks, but this rock is made up of mineral crystals - I hope that makes sense and if not I will clarify!

I can't see the stone well enough to say what's what, but most likely the bulk of that rock is feldspars of different sorts. The white, grey or green minerals are likely feldspar. Quartz grains look glassy and translucent - you can actually see into the stone with quartz. So you might have some quartz in there too. The black is either hornblende or biotite. If you post a closeup of it I can probably give you a clearer answer. But for all intents and purposes that's granite. And it sounds like it's a winner for you too, so that is perfect!

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RE: The lowdown on Super White (Follow-Up #17)

posted by: donaleen on 10.27.2012 at 02:07 pm in Kitchens Forum

Sorry, forgot to answer your question.

And, yes, very easy to care for. No issues at all. And we cook a lot.

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RE: The lowdown on Super White (Follow-Up #16)

posted by: donaleen on 10.27.2012 at 02:05 pm in Kitchens Forum

Thanks, Island. The "granite" changes a lot with the light. In the day, it is more green. With artificial light, it becomes more gold. I love it in both lights.

Here are LOTS of pictures.

Here is a link that might be useful: my kitchen

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RE: The lowdown on Super White (Follow-Up #15)

posted by: island on 10.27.2012 at 01:55 pm in Kitchens Forum

Karin- another question about marble. So many people worry about how it will wear in the kitchen, but use it freely in their bathrooms from top to bottom. Between cleaning products, soap, shampoo, toothpaste, makeup, hard water, etc wouldn't it get even more beat up in the bathroom? I don't get it.

Donaleen- a couple of my friends have seafoam green granite and looks very similar to yours which is beautiful. They have no problems with theirs, Is yours easy to care for also? Can you share a wider view of your kitchen. I'd love to see more of how your white cabs look with the green granite. I love green.

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RE: The lowdown on Super White (Follow-Up #14)

posted by: lexmomof3 on 10.27.2012 at 01:44 pm in Kitchens Forum

Thanks for the info! What are your thoughts on Macabus quartzite? Is it a quartzite or marble? After Beekeeper's challenges with the etching on her SW I am leaning towards Macabus but wonder if it is just the same.

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RE: The lowdown on Super White (Follow-Up #12)

posted by: donaleen on 10.27.2012 at 01:14 pm in Kitchens Forum

karin,

That was a fascinating and well written bit of information. I hope you keep writing more about it.

We have "granite" in a green/black/gold color, all mixed together from different rocks. I bet it isn't "granite" but is some "feldspar" like I think you said.

I wasn't nuts about getting granite but I really love what we ended up with. It has lots of "rocks" in it and is performing and looking good. It was sold as Brazilian emerald green but doesn't look that much like any emerald green I've seen pictured.

Whatever it is, I like it very much.

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RE: The lowdown on Super White (Follow-Up #11)

posted by: karin_mt on 10.27.2012 at 09:29 am in Kitchens Forum

Yes, Beekeeper's Wife, you do have marble, albeit dolomitic marble if you want to sounds like a smartipants to your friends. :) That said, you have absolutely stunning marble!

The hard water thing confuses me. Are you sure that it's an etch rather than a small area where minerals have been deposited on the surface? (meaning an etch is a subtraction of materials but could this be an addition of material?)

Almost all tap water is slightly acidic, but hard water is not more so that soft water. I'll have to think more about the chemistry here. If this is a true etch, then there must be something going on with the minerals in hard water (which aren't all that different than the minerals in marble). Hmmm. Will think about it.

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RE: The lowdown on Super White (Follow-Up #10)

posted by: karin_mt on 10.27.2012 at 09:23 am in Kitchens Forum

OK, now that I'm awake and accompanied by coffee, I will clarify that I really do love the marbles and stones like Super White. I am definitely not saying that someone should rule them out, or worse yet, that if you have them it was a bad choice. There is a reason those stones are so in demand and it's because they are wonderful and nothing else can quite match their aesthetic.

My point is just to warn folks to be informed, regardless of what a stone is called. But I don't want to make anyone feel bad about their decision!

Karin

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RE: The lowdown on Super White (Follow-Up #9)

posted by: beekeeperswife on 10.27.2012 at 09:22 am in Kitchens Forum

Interesting.

So I DO have marble. I guess the saying is true..

"If it looks like marble, and it acts like marble, it is marble." That's a saying, right?

Any info on why my extremely hard water etches it? Or leaves gray spots if that isn't really "etching"? (No water softener yet, but at last my dh is having some issues getting soap off during showers so it might be getting pushed up the priority list)

Thanks

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RE: The lowdown on Super White (Follow-Up #8)

posted by: karin_mt on 10.27.2012 at 01:41 am in Kitchens Forum

Well, I'm glad to see this is useful info for folks! I can answer a few questions before bedtime here.

What is the hardest marble?
Sadly, none of them. While I'm sure some are slightly better than others, they are all just 3 on the hardness scale. OK, maybe dolomite is 3.5, but quartz is 7, feldspar (the most common ingredient in granites) is 6. So there is no way to prop up a 3 to make it a 6.

For comparison, glass is around 5 and steel (like utensils) is around 6. So for a kitchen I would not be keen to have common kitchen objects be harder than the countertop.

That said, the hardness scale only addresses resistance to scratching. Hardness does not tell you how strong the rock is in terms of resistance to breaking or chipping. A rock's strength is based more on planes of potential weakness within the rock and in that regard marble is pretty good.

Etching is another matter altogether. Etching is a chemical problem and is not related to strength or hardness. Etching is also a fact of life for any rock with calcite or dolomite in it. Acids dissolve calcite and there's just no way around it. So this includes all marbles and limestones, travertine and perhaps some of the onyx type stones, although I have to figure those out some more. Dolomite is a little more resistant to dissolving than calcite, but not much.

Bottom line - in my geologic opinion, all of these stones require careful consideration before using them in a kitchen. But I will admit that I swoon every darned time I pass by a slab of white marble. I just love it! But I will have to come up with another place to use it, like as a mantle or a countertop on a china cabinet.

As for soapstone - it is even softer than marble. But you don't have the etching problem. But with soapstone it is easier to consider the scratches a patina and just let that be part of the rock. Soapstone has a warmth to it that somehow doesn't seem so bad with some scratches in it. There are some igneous or metamorphic rocks that have the same color or soapstone but they lack that warm quality that soapstone has.

What's with black granite?
This is mostly an academic concern not a usability issue. Black rocks that are called granite in the context of a countertop are just some other type of igneous rock. They are diabase, gabbro, diorite, anorthosite, and so on. No one wants to remember all those names. As far as use and durability in a kitchen, all those rocks will perform just as well as granite. In most cases, black granites and true granites are mostly feldspar - but they are different types of feldspar and different colors.

A true granite is an overall light color with some black specs. The overall color is grey, tan, pink, etc, but they are more light than dark. But igneous rocks range from pale to jet black and in terms of kitchen suitability they are all similarly robust. So I can see why they are all just called granite for the sake of simplicity.

Will I go shopping with you?
Absolutely! I love spending other people's money. :)
I'm in Montana. (where it is currently bedtime, so I will leave it at that for now)

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RE: The lowdown on Super White (Follow-Up #7)

posted by: Angie_DIY on 10.26.2012 at 11:21 pm in Kitchens Forum

That is really interesting about the Super White. That would explain why some people's experience with SW, which they bought thinking it was a quartzite, is that it etches easily. Thanks for sharing your knowledge.

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RE: The lowdown on Super White (Follow-Up #6)

posted by: island on 10.26.2012 at 09:38 pm in Kitchens Forum

I'd also like to know what are the black "granite" stones? Thanks.

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RE: The lowdown on Super White (Follow-Up #5)

posted by: a2gemini on 10.26.2012 at 09:06 pm in Kitchens Forum

Interesting - we will have to have you analyze more stones...
Thanks

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RE: The lowdown on Super White (Follow-Up #4)

posted by: berardmr on 10.26.2012 at 08:55 pm in Kitchens Forum

I would love your opinion of what type of marble is the hardest and most resilient. Thanks!

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RE: The lowdown on Super White (Follow-Up #3)

posted by: mpagmom on 10.26.2012 at 08:30 pm in Kitchens Forum

So what are the "black granites"?

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RE: The lowdown on Super White (Follow-Up #2)

posted by: 2LittleFishies on 10.26.2012 at 08:23 pm in Kitchens Forum

Interesting! I don't remember the specifics of who has what stone but from what I recall some here have SW and say it acts like granite (no etching, etc) and others have had the opposite experience and it etches.

Thoughts? Are these all different stones in reality and not all Super White?

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RE: The lowdown on Super White (Follow-Up #1)

posted by: ppbenn on 10.26.2012 at 08:13 pm in Kitchens Forum

Thank you so much for sharing your expertise Karin.
With all of the different stones, different sources, different names it is unbelievably confusing.
I'm looking at finding a black hard soapstone and some kind of a white marble looking, granite acting stone for the island and bath counters. This should not be difficult, but wow it is challenging!
Where are you located? And would you be available to come stone shopping with me ;)

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The lowdown on Super White

posted by: karin_mt on 10.26.2012 at 07:01 pm in Kitchens Forum

I am mostly a lurker here so far, and as our kitchen remodel plans take shape I have been enjoying seeing other people's progress and taking comfort that there is a strong community of kindred spirits who like to sweat all the glorious details of a kitchen!

I'm a geologist so perusing the slab yard is always fun. Rarely do you get to see so many fascinating rocks all in one place.

So today when I picked up my backsplash tile and put down a deposit for some small slabs (a separate story), I had a great time visiting various slabs with one of the fabricators. We talked about the minerals and textures that make some rocks winners in the kitchen, and others not so good.

I asked to see some Super White, knowing there is a lack of clarity about what this rock really is. He gave me a piece to bring home and I did some diagnostics. Maybe this is common knowledge to you all, but here's the lowdown.

The rock is dolomitic marble. It's not quartzite - it's not even close to quartzite in terms or hardness or resistance to acid.

Dolomitic marble is a sibling to regular marble. Regular marble is made of calcite. Dolomite is made of calcite plus magnesium. Calcite is CaCO3 and dolomite is CaMgCO3. So this rock started out as the sedimentary rock called dolomite then was metamorphosed (heat + pressure) to cause the grains to recrystallize into dolomitic marble.

My hunch is that this marble would be slightly more resistant to etching than regular calcite marble. But it is still just as soft as marble and has all the other requirements of caring for marble. It sure is a beautiful rock. But no way will it wear like granite or quartzite.

The decorative stone industry has a whole different way of naming and classifying rocks than geologists do. (The first time someone showed me a back granite I protested loudly. There is no such thing as black granite!) But I am coming around to understand how the rocks are classified from the countertop point of view. So yes, the terms are contradictory and confusing, perhaps even deliberately so in some cases. But at least in this case I am certain of what the actual rock type is.

I hope that's helpful or illuminating. And if you have questions about the real identity or geologic history of your countertop, I may be able to shed some light!

Karin

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RE: You know you have induction when... (Follow-Up #37)

posted by: luv2putt on 06.19.2012 at 03:39 pm in Appliances Forum

when your range is totally cleaned up before your food is finished cooking and served !!!!

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RE: You know you have induction when... (Follow-Up #35)

posted by: Ginny20 on 06.18.2012 at 12:05 pm in Appliances Forum

the air conditioner breaks, temp's in the 80's, and you're having guests for dinner, but you can still cook because it won't heat up the kitchen.

a2gemini - Let us know how that griddle does. I need one, too.

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RE: You know you have induction when... (Follow-Up #34)

posted by: mojavean on 06.17.2012 at 09:11 pm in Appliances Forum

You attract swarms of horny bumblebees every time you make an omelet.

You have to call in scientists from CERN to analyze your "boil patterns."

Your Gramma's old cast-iron griddle shrieks in horror on pancake day.

You honestly know what Sil-Pat is.

And, to be fair:

You have the most efficient, most responsive and temperature-steady means of cooking known to human-kind short of psychic barbecue which is not widely available.

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RE: You know you have induction when... (Follow-Up #33)

posted by: mtc1 on 06.17.2012 at 07:43 pm in Appliances Forum

You have Thermador gas range but you and your husband wait in line to use the portable induction unit you got from Williams Sonoma!

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RE: You know you have induction when... (Follow-Up #32)

posted by: plllog on 03.18.2012 at 11:58 pm in Appliances Forum

...you say, yes, of course I'm putting the glass bowl down on the cooktop--it's not on the hot part.

(I did broil some peppers today, for the soup, and they did get charred, though not as thoroughly as on a flame. As Westsider said, that's what the rest of the appliances are for...)

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Charring? not a big deal (Follow-Up #31)

posted by: westsider40 on 03.18.2012 at 09:50 pm in Appliances Forum

you realize that charring can be done in either of your two broilers or on your back porch Weber. It is so not a big or often, deal. How often do you char, really?

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oh, yes (Follow-Up #29)

posted by: westsider40 on 03.18.2012 at 09:33 pm in Appliances Forum

you don't need the romance of flames to cook evenly, powerfully and with military precision.

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RE: You know you have induction when... (Follow-Up #28)

posted by: westsider40 on 03.18.2012 at 09:22 pm in Appliances Forum

You are never too tired to clean up after dinner. Swish, all done.

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RE: You know you have induction when... (Follow-Up #27)

posted by: AnnaA on 03.18.2012 at 08:52 pm in Appliances Forum

... You see, perhaps for the 1st time, how much energy gas stovetops waste.

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RE: You know you have induction when... (Follow-Up #25)

posted by: plllog on 03.17.2012 at 08:49 pm in Appliances Forum

...you turn the power down to brown meat.

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RE: You know you have induction when... (Follow-Up #23)

posted by: plllog on 03.17.2012 at 06:07 pm in Appliances Forum

...when watched pots do boil. Fast.

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RE: You know you have induction when... (Follow-Up #21)

posted by: suburbanmd on 03.17.2012 at 11:37 am in Appliances Forum

...cooking no longer means "slaving over a hot stove".

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RE: You know you have induction when... (Follow-Up #20)

posted by: AnnaA on 03.16.2012 at 11:50 pm in Appliances Forum

...love NOW means never having to say you're sorry for using electric!

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RE: You know you have induction when... (Follow-Up #18)

posted by: plllog on 03.16.2012 at 06:36 pm in Appliances Forum

...your friends and neighbors are impressed by your ability to boil water.

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RE: You know you have induction when... (Follow-Up #17)

posted by: weedmeister on 03.16.2012 at 05:49 pm in Appliances Forum

...you have a portable propane grill strictly for grilling chilis.

... you use a Bic for Flambe's.

... you gave your mom all the ceramic cookware.

... your MIL says "I'll let you cook since you seem to enjoy it more than me."

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RE: You know you have induction when... (Follow-Up #16)

posted by: mojavean on 03.16.2012 at 01:02 am in Appliances Forum

No matter how long you roast your chiles they still won't peel.

You have mastered the technique of "Flambe of the Mind."

Your old "Visions" cookware dies of loneliness.

Your Mother in law calls you at the theater to announce that the burners on your stove won't get hot.

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RE: You know you have induction when... (Follow-Up #15)

posted by: lalitha on 03.16.2012 at 12:11 am in Appliances Forum

Your relatives and friends are suddenly getting *gently used* previously treasured calphalon and aluminum based cookware.

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RE: You know you have induction when... (Follow-Up #13)

posted by: plllog on 03.15.2012 at 09:44 pm in Appliances Forum

...you keep a Bic lighter by the stove for lighting birthday candles, and it never blows up.

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RE: You know you have induction when... (Follow-Up #14)

posted by: AnnaA on 03.15.2012 at 11:19 pm in Appliances Forum

Every purse and bag you own is packing magnets.

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RE: You know you have induction when... (Follow-Up #11)

posted by: kashmi on 03.15.2012 at 09:30 pm in Appliances Forum

... your very undisciplined, counter-surfing dog licks the spills on the cooktop right after you finished cooking.

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RE: You know you have induction when... (Follow-Up #9)

posted by: dodge59 on 03.15.2012 at 08:32 pm in Appliances Forum

You pour some water in a pan.
You set the hob to on, but at the lowest setting.
You leave it there for 4 hours.
Then you remove the pan, and immediately drinks the
water , "Straight from the pan"! (Carefull not to spill any).

Gary

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RE: You know you have induction when... (Follow-Up #7)

posted by: plllog on 03.15.2012 at 03:32 pm in Appliances Forum

...you get nervous about leaving the potholder next to the pot because it might get dripped on, not because it might catch fire.

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RE: You know you have induction when... (Follow-Up #4)

posted by: AnnaA on 03.15.2012 at 02:23 pm in Appliances Forum

The pan is ready before you are.

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RE: You know you have induction when... (Follow-Up #3)

posted by: lalitha on 03.15.2012 at 02:37 am in Appliances Forum

You show off to friends by offering them tea.. "it will only take a jiffy... Here you go"

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RE: You know you have induction when... (Follow-Up #2)

posted by: plllog on 03.15.2012 at 01:23 am in Appliances Forum

...you set a pan on the heat to season and totally forget it, but your pan is fine because the cooktop got tired of waiting for you and turned itself off.

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You know you have induction when...

posted by: plllog on 03.14.2012 at 10:42 pm in Appliances Forum

...you turn off the stove when you've just started a pot of pasta water to go to the bathroom because it might boil over before you get back.

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RE: Picked appliances - I am stuck with the hood decision - need (Follow-Up #4)

posted by: kaseki on 03.30.2013 at 09:23 pm in Appliances Forum

The air flow rate (cfm) required is not a function of the BTU rating (unless it is too low to cook anything). It is a function of the need to contain the uprising effluent. The rough requirement for CFM is 60 s/min times the product of the effluent velocity (~ 3 ft/s), the aperture area collecting the effluent (sq. ft), and some efficiency factor accounting for aerodynamic effects at the baffles (maybe 0.5). (Note that for flush mesh filters the area is the size of the mesh times the effective clear area ratio, something not so easy to account for, particularly for complex mesh structures.)

Further, the CFM calculated above should be the actual CFM achieved. Hood and duct transitions, baffle friction, duct friction, house negative pressure due to imperfect MUA will cause the hood blower to move less air than it is rated for. People who have lived with recirculating hoods, or OTR microwave oven ventilation, or the poser kitchens widely published in the media that have no ventilation, will be able to get away with less flow and still be ahead of where they were.

The aperture has to be large enough to capture the expanding uprising effluent. Expansion half angle varies around 22.5 degrees from every point on the pan surface hot enough to cook and generate water and grease vapor. The hood aperture should overhang the locus of these projected points at the planned height of the hood.

kas

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RE: Blower Recommendation for Wolf Pro Island Hood (Follow-Up #10)

posted by: kaseki on 11.23.2007 at 07:08 pm in Appliances Forum

Actually, the good stuff in those articles, once one converts from metric to more common units used in US HVAC description, is the effluent velocity, volume rate, and expansion angle. Of significance are the heating efficiencies of the burner types, and the adjustment factors for the equation - widely used in Europe apparently - for finding the cfm vs height above the cooktop, heating power in the plume, hydraulic diameter, etc.

The hood system has to capture, contain, and evacuate. Capture requires that the hood overhang the expanding effluent plume, which expands at about a 7-degree half angle. Contain means that the stuff not curl in the hood and come back out. That is partly determined by hood design, but also by air velocity keeping the effluent velocity from being redirected. Having a cfm high enough that the air velocity at the entrance to the hood be as high as that of the effluent velocity should be plenty, possibly overkill unless the airflow is easily disturbed from movement in the room or replacement air velocity being too high near the hood. Flow around the edges of the hood vs. the lower effluent velocity at the edges of the plume can be a factor in adjusting the velocity requirement. And evacuation results from having a cfm at least that of the effluent and generally more to meet the containment velocity requirement.

kas

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RE: Blower Recommendation for Wolf Pro Island Hood (Follow-Up #12)

posted by: kaseki on 11.25.2007 at 06:03 pm in Appliances Forum

PART 2

We next consider using a 34-inch by 48-inch Wolf hood to provide adequate overlap of the plume to handle expansion in the hood and plume deviations due to air disturbances in the kitchen. The diameter of the plume at one meter is shown in the papers to be under 34 inches.

The actual entrance area of the Wolf Pro Island Hood of these dimensions is unknown to this author. There appears to be a slight return on the edges of the hood, and there are switches inside one edge. We guess that the actual entrance area is 10 square feet. (32 in by 46 in is 10.22 sq.ft.)

300 cfm divided by 10 sq. ft. leads to an average air velocity at the hood entrance of 30 ft/min. However, interpolating the results for the induction range in the part 2 article, the peak velocity of the plume studied was 0.66 m/s or 130 ft/min. This will vary with cooking temperature, but we are using a average over the cooktop so it shouldn't be too far off.

What happens when a plume with a nominal Gaussian velocity distribution and central velocity of 130 ft/min enters a hood with an average intake velocity of 30 ft/min? The plume reaches to top of the hood and the higher velocity part spills downward. It is unlikely it will all reach 30 ft/min and be perfectly captured before some of it spills out.

If the entire hood entrance were provided an average airflow of 130 ft/min to ensure capture without any roiling, then the cfm required would be 1300 at the hood entrance. The roof fan that could achieve this would likely be rated 2000 cfm at zero static pressure. Probably (we hope), 1300 cfm is overkill because much of the plume is well under 130 ft/min.

[handwaving begins]
If we assume that the baffle entrances are 40% of the hood aperture, and consider that the roiling plume has to pass close to baffle entrances with airflows thus 2.5x that of the average, then a 600 cfm average airflow would yield baffle edge air velocities of 2.5 x 60 or 150 ft/min. This might be enough for sufficient capture. Here we are hoping that spilling effluent is slowed down and is drawn into the higher speed baffle entrances before any can leak out of the hood and contribute to kitchen odor.
[end handwaving]

Wolf recommends for a 36-inch induction cook-top a 600 cfm fan. This is fan cfm at zero static pressure, so they are likely actually expecting somewhat less at the hood, maybe 400.

We would choose 600 real cfm for this case to be safe and use a nominal 900 cfm roof fan to obtain it (pending analysis of all the pressure losses involved). This rate will be higher than needed for many cooking conditions, but the roof fan can always be turned down. Running at reduced power reduces noise, and beats kicking oneself for not having enough power when the need arises.

Schlieren photography of this hood and cook-top combination (or a very elaborate computational fluid dynamics analysis) would be needed to determine the true minimum cfm that ensures full capture and containment.

kas

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RE: Blower Recommendation for Wolf Pro Island Hood (Follow-Up #11)

posted by: kaseki on 11.25.2007 at 05:17 pm in Appliances Forum

The following is an example calculation pitting a nominal Diva induction cook-top against a Wolf Pro Island Hood. As the reader will find, some hand-waving is needed to close on a required cfm.

PART 1

We need two conversion factors:

To get ft/min from m/s, multiply by 197
To get cfm from m^3/s, multiply by 2119

First, we look at what the induction cook-top effluent plume characteristics are.

We assume that the entire 9.6 kW maximum power output of the Diva 36-inch cook-top is being used, and that the pan configuratin is such that the heated surfaces have the same area as the cook-top. The first assumption is unlikely and hance conservative, and the second has only a second order effect on the result.

Using the methods of the referenced papers, we can find that the hydraulic diamter D_h is 0.64m. We want a hood that is over our head, so we choose 1-m height about the cook-top. (Higher means larger cfm.) Of the 9.6 kW output by the Diva, only 6% heats the air per the referenced experiments. Hence the convective heating is 0.576 kW.

We use the equation:

q_v = 0.05*((z + a D_h)^5/3 * phi^1/3)

where a is 1.7, z is 1m, and phi is 0.576 kW

(The papers use a coefficient of 0.05 in one place, and 5 in another, and claim phi is in watts but their tabulated results require phi to be in kW.)

Solving the equation and converting to cfm leads to 300 cfm in the convective plume from all 5 hobs.

continued below

kas

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RE: Facts about Granite Slab Quality Variables (Follow-Up #9)

posted by: SaraKat on 02.04.2013 at 07:13 am in Kitchens Forum

Thanks very much oldryder, that's the information I've been needing. I thought this was the problem.

The supplier granite yard is out of business and the fabricator although it was one of their suppliers says there is nothing they can do about it.

The only reason we are looking at replacing is that we have the problem with shedding, the awful feel of this stone that feels dirty and like it is covered with tiny pepper grains no matter how many times I wipe it down. It snags my dish cloth and the sink recently cracked and has to be replaced. The sink is a mystery as to why that happened.

Thank you so very much I will check in to the Hydro Shield and hopefully it will make it more tolerable. The island is the worst thank goodness since we could just replace that to keep down the cost. I really wasn't planning on an expense like this coming up this soon! It hasn't even been a year yet. The granite fabricator gave me a replacement price for new granite of $4500 which is the same as we paid for the original granite and it was supposed to be their super discounted price ....sigh. Live and learn, thank you very much again.

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