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karin_mt_2

Countertop Geology, Part 5: Marble, Quartzite and other Favorites

karin_mt
10 years ago

This is round five of the Great Rocks Thread!

Please post your rock questions here. I've copied the basic info about quartzite and marble here because this is the most frequent question.

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 and the etch test.

Scratch Test
Take a glass bottle or a glass tile 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 in your hand. You shouldn't need to press that hard!

Etch Test
Etching is when the surface of a rock is dissolved from acids like lemon juice, vinegar, wine, etc. It is the primary bummer about using marble in a kitchen. Etching is most noticeable on polished rocks. Etching is not prevented by sealers, no matter what you hear from the sales rep!

Doing the etch test is simple: bring home a sample of the rock and put lemon juice or vinegar on it. Even after a few minutes the results are usually obvious. Etched areas look duller and are discolored compared to the rest of the slab.

Some people get conflicting results with these two tests, but normally anything in the marble family will not scratch glass and it will etch.

Quartzite and rocks in the granite family will scratch glass and will not etch.

For reference, here are links to the other rock threads, in which many types of rocks have been discussed.

Rocks 101: The Lowdown on Super White

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

Rocks 103: Countertop Geology: Marble and quartzite and granite, oh my!

Rocks part 4, Marble, Granite, Quartzite

With that, let the rock conversations continue!
-Karin

Comments (168)

  • polkadotz
    9 years ago

    Oh my gosh, I've just read through all the rock threads. WHEW. karin and many others of you have been a fount of knowledge. Thank you!

    I visited a slab yard in Anaheim the other day. I went in thinking that I wanted quartzite because of it's durability but secretly I wanted marble. I got a wonderful salesman, who happened to be the factory's manager in Italy. (He was in town because his wife had had a baby and they were visiting family.) He showed me the white macaubus quartzite he had in stock which was not very WHITE at all. The only other white looked like a super white or princess. i asked him about those slabs and he said although they are grouped here with the quartzite they're dolomitic marble and not as hard as quartzite. Wow! I was shocked that he was so knowledgable and forthright. I was expecting the worst after reading this thread. After that, he pointed me toward the marble section and we talked through all the options there. He showed me an 8 year old countertop (someone had returned b/c they were remodeling kitchen and needed a larger slab.) He showed me what the etching and patina and stains looked like. I decided they didn't diminish the beauty of the stone and I could get over it.

    I found some beauties. My favorite is a type of carrara called Bianco Venetino, seen in the photo. My question is... within the marble spectrum, is there anything I need to know about the different varieties? Other than price and looks, what do I need to consider? Honed vs Polished? Leaning toward a 3" mitered edge. This is for my island which will be 10'x4'. The rest of kitchen will probably be Caesarstone Raven.

  • karin_mt
    Original Author
    9 years ago

    First off, congratulations for reading all 5 threads! For that, you get an honorary degree in Countertop Arts and Sciences.

    Sounds like you are going into your marble decision with eyes wide open, so good for you. As you've already learned, dolomitic marbles are a little bit more resistant to etching compared to the pure calcite types. Honed vs polished is personal preference. Some people say honed shows less etching, some say the reverse.

    Probably the most important thing is to test a sample of the actual rock - that will tell you more than anything.

    Your slab is gorgeous - glad you are having a good experience with the shopping!

  • annabelle6
    9 years ago

    Have made it through all five posts (what incredible amount of information,) as I now am searching for a creamy colored countertop for my island. Not a fan of marble but granite is so spotty to me it's difficult to find something that has more gentle movement. Found this piece of Dolce Vita and will go back to do the test but wondered if you would encountered it before Karin? It doesn't seem to be much traffic on this "quartzite". Any thoughts?

  • karin_mt
    Original Author
    9 years ago

    Hi Annabelle,

    That's a pretty one, but I'm not familiar with it. Just looking at it, it could be either quartzite or marble, can't tell from here. Let us know what the tests turn up, good luck!

    Karin

  • scaredreno
    9 years ago

    I just found this thread and I have a super white question. The stone yard that I'm dealing with lists it as granite. My fabricator says its quartzite. But then everywhere I look, people say super white is marble. The same stone yard also carries (and lists differently) arabescato quartzite which i read is also known as super white. The woman at the stone yard told me that arabescato quartzites is like marble so steered me away from it. With super white, she said it was very durable and strong like granite. My fabricator says the same and I was able to scratch glass with the corner of it (the sample that they gave me was clean cut so I just used the corner). What am I missing here?

  • scaredreno
    9 years ago

    One other question. Loved a quartzite called frosty white. It's white with speckles of silver and gray. kinda looks like snow. my fabricator says that super white is more durable. anyone know about that stone?

  • christina222_gw
    9 years ago

    The only way to be sure is to do all the tests these geology threads recommend. Stone yards label everything pretty randomly. Some Super White is actual quartzite, some is marble. Same with a lot of other stones. Get a sample, take it home. Do the scratch and acid tests. If it passes, it's probably quartzite.

  • scaredreno
    9 years ago

    thanks. everywhere i looked people said super white was a slightly stronger marble. i'm doing the test. the scratching was hard to do because i only had the edges (the sample i had was a clean cut), but after a few tries with the corner, it did scratch the glass. i'm using red white and pickle juice on tissue papers and leaving it on the sample over night. that's sufficient right? we'll see what happens.

  • karin_mt
    Original Author
    9 years ago

    That's right, you can only try the scratching with the edges of the rock. If the sample is yours to keep you can break it and get lots of edges.

    Some Super White may scratch glass weakly on inconsistently, because it sometimes can have some quartz in it. So you have to do both the glass test and the etching test.

    If your sample took a few tries to scratch glass, my guess is that it's not quartzite. Quartzite really gouges glass. :)

  • robynstamps
    9 years ago

    Just wanted to thank all of you (especially Karin) as it helped me to finalize my quartzite choice about a month ago. It's called Brazilian White Quartzite and it is beautiful. The picture doesn't do it justice. It actually reminds me of a granite in person but has the feel of quartzite.

  • karin_mt
    Original Author
    9 years ago

    Wow Robyn, that is one amazing slab. Nice job in finding something so beautiful as well as functional. I'm sure you will love it in your kitchen for many years.

  • scaredreno
    9 years ago

    @Karin_MT So I did the etch test and i guess it failed. There was slight etching, You couldn't see it unless you looked at it at a particular angle, and my husband couldn't see it at all (but then he's generally blind about these things). does less etching mean more quartizite in the slab or the does the fact that it etches at all mean that it's dolomite. I will try breaking the piece apart to get a better edge to see. it does leave a nice sized scratch but only one corner seems to do it.

  • scaredreno
    9 years ago

    one other question, will sealing help with the etching problem at all or is sealing completely useless when it comes to etching?

  • karin_mt
    Original Author
    9 years ago

    Your results sound exactly like dolomitic marble that has a small amount of quartz in it, which is what Super White is.

    Mostly the less etching is because it's dolomite rather than calcite. The dolomite is slightly resistant to etching. The small amount of quartz doesn't really affect the etching situation, since it's a tiny amount of the actual surface area. All that quartz does is confound the scratch test results.

    Sealer does not help with etching. It does help with staining, but that's it.

    Well, it sounds like you have done an excellent job gathering the facts about your stone, and now you can make an informed decision.

  • scaredreno
    9 years ago

    Thanks for all your help. I really like the stone so I think I will end up going with it, but I'm not happy about what I was told by both the stoneyard and fabricator. One last question, is it hard to find pure quartzite? I found one slab (it was white with speckles of silver and gray) that I really liked but it was super expensive (more expensive than the super white, it was called frosty white and i think i saw it at another stone yard and they called it snowy white). I didn't get a slab of that, unfortunately. The fabricator told me that that stone was more prone to etching and softer than the super white but from what he told me about my super white stone, not sure I can actually believe him.

  • scaredreno
    9 years ago

    Here's a link to the frosty white that i liked. http://nash-inventory.smugmug.com/Other/QUARTZITE/i-KMPjHqV/A

    any info that anyone can give me on this stone would be greatly appreciated. Thanks.

  • karin_mt
    Original Author
    9 years ago

    Yeah, I don't get why some industry people don't seem to make a more concerted effort to get the facts right. Nonetheless, you got it right, so you can make the right choice!

    Real quartzite is not hard to find, although it is expensive and you really have to always check it for yourself since they all can look so similar. But White Macabus (which, I think is the one called Classic White in the gallery you posted), Calcatta Macabus (perhaps Carcalc from the gallery), Madra Perla, Taj Mahal, and Sea Pearl are some examples of real quartzite. Of course, the names are all jumbled up, so you really have to be ready to do a lot of testing.

    The pure white slab you posted - hmm, if I had to guess I'd guess marble. But I shouldn't even make guesses because you really can't tell visually, particularly from just a photo. But I don't think I've ever seen a pure white quartzite in slab form. I've seen them out in the field, but never in commercial form, so to speak.

  • scaredreno
    9 years ago

    the white has that crystallized look. it doesn't appear to be etching, but I can't scratch glass. is that possible?

    This post was edited by scaredreno on Thu, Sep 4, 14 at 21:12

  • karin_mt
    Original Author
    9 years ago

    Huh, that doesn't make a lot of sense. My advice would be to try both again. On the scratching, make sure you have a sharp edge to scratch with.

  • scaredreno
    9 years ago

    follow up: it etched. hard to see because the sample i got was in such bad shape as it. also scratched very easily. something, i assume real quartzite wouldn't do. now i'm going to take a look at macauba at the stone yard. will test to see how that fares. don't love the look, so if it passes, i'm going to have to make the hard choice between practicality or looks. not looking forward to it. ;-)

  • kitchendetective
    9 years ago

    Some on that site look like sandstone. One looked like onyx. Fun to look, if not being pressed for a decision.

  • karin_mt
    Original Author
    9 years ago

    Agreed kitchendetective, love those stone galleries as pure eye candy!

    Well, Scaredreno, at least that second result makes sense. So that is marble after all.

    Look for the crosscut version of Macabus, I thought I saw it in the gallery, called Carcalc. Geez, for all those slabs they are calling quartzite, you'd have to hope that a least a few of them actually are. The question is do you have the patience to sort that all out. (Of course the much bigger question is why do they mislabel them in the first place!)

    Keep chipping away at it (nice pun, right?). You'll find the right one.

  • scaredreno
    9 years ago

    so i think i found it. tested the sample. passed both! and i kinda like it (although it has somewhat of a greenish/beige tint that i'm not sure of), but overall more practical for my kitchen. it's crosscut which i like better than the veincut.

  • karin_mt
    Original Author
    9 years ago

    Yeah, that's the one I was thinking of! Very good that it passed the tests, great job with that. Now you have to think about the aesthetics. Personally, I love it, but it's your kitchen so you need to mull it over.

    Exciting though, you are getting closer!

  • susanlynn2012
    9 years ago

    scaredreno, I love the slab you chose in the last picture above!

    Annabelle6, I just love the Dolce Vita counter slab you just shared!

  • christina222_gw
    9 years ago

    That's a gorgeous slab Scaredreno! When I chose my slab the only thing that gave me pause were some soft waves of greenish blue in the stone. Now, of course, those are my favorite parts of my counters!

  • lisa_a
    9 years ago

    Karin, these threads are so informative, thanks to you and the other experts (oldryder, Treb, I'm forgetting someone, sorry) for sharing your expertise and thanks to GWers for sharing their experiences, too.

    I'm looking at 3 white granites but I'm not able to find much about them, specifically their water absorption rates. I hope you can help me.

    IIRC the info in these thread (so much info, my brain is spinning and I'm sure I've forgotten at least half of what I learned), these are true granites and might possibly be gneiss, so they should be tough stones but might stain. Is that correct? We plan to seal anyway since we want the stones to be honed or leathered (we're not shiny surface people). Can you tell me anything about these stones?

    Thank you!!

    We're doing leathered Steel Gray on the perimeter, the above are options for the island.

    {{!gwi}}

    The Steel Gray (aka Silver Pearl, I think) is tough as nails. I left lemon juice, ketchup, mustard ... can't remember what else I tested on them but everything wiped up without leaving any evidence behind. I left a puddle of water sitting on it for hours. When I wiped it up and dried the surface, there wasn't even a tell-tale mark of darkness where the water had been. And it hasn't even been sealed yet.

  • missymoo12
    9 years ago

    Lisa those slabs are beautiful and we are contemplating similar white ones but with different names. Where did you find these? Just want to know if its close to my area.
    You are right the Steel Gray is bullet proof. It's my option if I cant get soapstone.

  • lisa_a
    9 years ago

    Thank you, missymoo12! I'm in the Portland Oregon area. Are you, too?

    I'm going in today to see how they look with my paint colors and backsplash tiles. Fingers crossed that one or all of them work because I am *not* going to start from scratch on those choices. I love them too much.

    If none of the granites work, I'll stick with PentalQuartz Carrara we originally chose. It's pretty and goes very well with our other choices. So why am I still checking granite yards? Because I'm slightly crazy. ;-)

  • kksmama
    9 years ago

    Lisa_a, your choices are lovely! I think I like the wine river leathered. Don't worry about being "slightly crazy", you are in good company. One could even say some of us have "rocks in our heads".

  • lisa_a
    9 years ago

    Thanks, kksmama! They are just as pretty IRL as they are in the pics, no wait, make that, they are prettier IRL than they are in the pics. ;-) If I was starting from scratch with my kitchen selections, I'd be hard pressed to decide which one to choose. But I'm not. They all look great with our perimeter counter but it's a mixed bag when it comes to how well they look with our backsplash tiles and paint colors for the island and hutch cabs and the walls. Yes, I could pick different tiles and paint colors but we *love* the accent tile we chose.

    Of the slabs I posted above, Aspen White looks the best with our choices but I fear that it has too much movement for us. I have an inner ear disease so busy patterns can sometimes do a number on me (brings out my inner blonde, ha!).

    Wine River leans towards the taupe side of gray and that just won't do.

    Glacier White is very pretty and quieter than Aspen White, which is more to our liking but, hmm, I don't know.

    So I revisited Bianco Romano, a stone that hubby and I have stopped and admired many times and well, what do you know, it looks very good with our choices. So I picked a slab with quiet movement and put it on hold until hubby and I can look at it in a few days' time. This pic is a slab from the same lot:

    {{!gwi}}

    Next up, I need to call the fabricator and see about pricing to have leathered. The rep at the granite yard said it should come up with a fairly consistent texture, which is another plus. Here's a pic of it honed:

    [Traditional Kitchen[(https://www.houzz.com/photos/traditional-kitchen-ideas-phbr1-bp~t_709~s_2107) by Greensboro Kitchen & Bath Designers Cabinet Concepts, Greensboro

    Rocks in my head, yep, that describes me quite well!

    Karen_mt, I can find info on Bianco Romano but I'd still love your take on the stone, please. Thanks!

  • karin_mt
    Original Author
    9 years ago

    Oh my, we've filled up another thread!

    Replies to follow in part six of the continuing saga...

  • aaburr
    8 years ago
    last modified: 8 years ago

    @karin_mt

    So, hello. I'm Ashley Burr in Colorado. we brought home a sample of this lovely quartzite fusion before it was installed. We tested for etching--no problem. I was superficially aware of the confusion between marble and quartzite, but not familiar enough with these threads to apply the scratch test.

    2 months after we moved in, I started noticing micro chips and scratches EVERYWHERE. Even up against the wall where we don't do or put anything! It's hard to see in a picture. ...these are just some of the areas I marked for the slab rep to come see.

    We've had the fabricator come out. The builder. A rep from the slab yard. They all shake their heads and say "yeah, that's crazy. Shouldn't happen....bla blabla."

    I am convinced we paid $16,000 for a beautiful marble, NOT quartzite. But I'm having a difficult time getting anyone who should be responsible to own that and fix it.

    So, Karin, my question for you is what do you recommend at this point since I failed to heed your advice in the beginning? The vp of our builder came and looked at it today and said if we can find an expert who can verify that we didn't get what we paid for (quartzite) then they'd replace it; if it turns out that this is just what quartzite does--chip and scratch like crazy, then that's just our problem.

    We live in Colorado Springs, CO. We got our slab from Arizona tile in Denver.

    Tips on getting this resolved from anyone welcome!

  • karen_ohio
    8 years ago

    Ashley Burr post your comment on Countertop Geology Part six: Let's talk rocks some more! Hope I have that correct! It has continued over there. Karen_OH. Karin_MT has made recent comments, so it is still active.

  • aaburr
    8 years ago
    @Karen_Ohio do you think you could post a link to that thread? I can't find it. ...
  • karin_mt
    Original Author
    8 years ago

    Huh, this is interesting. And also very distressing for you Ashley!

    Have you gotten etches?
    Are the scratches all in the black parts? Or in the white parts? Or any pattern at all?

    Do you have a remnant piece from this same slab - or at least from the same batch of slabs? If so I can check it out for you.


  • aaburr
    8 years ago
    @karin_mt no, I'm so mad... we foolishly tossed the sample that we initially tested. I suppose we could ask for another but I'm not sure how helpful that would be since it likely wouldn't be from the same batch.

    the scratches and chips are random. everywhere. and the chips expose white underneath that I can dig my fingernail into. I don't know that I'm confident enough about what etching actually is to say. ...but there are rough, dull, patchy parts consistently found throughout the dark green portions of the stone. almost looks like hundreds of tiny cuts in the dark green.
  • karin_mt
    Original Author
    8 years ago

    OK, well we can say that regardless of the actual rock type, this stone is not suitable for use in a kitchen. It doesn't sound like quartzite to me with that behavior, at a minimum any material you can scratch into with your fingernail is definitely not quartz. It's also possible that it's mostly quartzite with some other material. That swirly pattern may indicate more than one type of mineral in the rock.

    So, you can make your case simply by saying that a rock like this is not appropriate for real-world use, particularly if its sold as quartzite.

    Option 2 is to go back to the stone yard and get a sample anyway, and see if you can replicate that behavior in the sample. And I am happy to have a look at the sample and help you figure out what it is.

    Looking at the AZ tile website, I see this:
    "During the polishing process, an epoxy resin is applied to the surface
    of the stone to fill in any natural pits, cracks or fissures that may
    exist. This does not affect the durability, maintenance or beauty of
    the stone. It is possible for some of the more minute pits that are too
    small to effectively hold the resin, to reopen during other finishing
    stages. However, this will not detract from the overall quality or
    appearance of the stone."

    Might this be the problem?


    Either way this is going to be tough to resolve, so proceed gently and hopefully you can get a fair outcome.


  • karen_ohio
    8 years ago

    I see you have met Karin_mt and I don't need to stay in the conversation. It is a lovely stone, though, I hope you can get a good resolution. Karin-mt, what is the title to Part 6?

  • karen_ohio
    8 years ago

    thanks! My Blue Pearl is still functioning well. I wish I had posted the pics on my old ipad before I turned it off. Now, I don't know how to retrieve any of the picutures.

  • aaburr
    8 years ago

    @karin_mt So let me ask you a few more questions then: Does genuine quartzite scratch and chip in that kind of fashion? Would it be reasonable to assume that I would have at least 100 little chips (not natural pits... chips that expose white) and scratches ranging in size from consolidated micro scratches to big gashes several cm long two months after we moved in if this was actual quartzite? Would it be reasonable to expect that to happen all over the stone, even in extremely low traffic areas, on a genuine quartzite slab?

    Is there any reliable way to test the stone that is installed on my counter to see what it is? ie whether it is actual quartzite or a marble? If so, how would I do that or who could I contact?

    I just find this to be extremely simple: I paid a small fortune for this stone because I thought it was beautiful and dynamic and all of the research I did on Quartzite as well as the info I was given from the slab yard indicated that it was harder than granite (which I have had in 3 other houses and NEVER seen anything like this on) and beautiful like marble. Thus the cost. So I am not a geologist, but it really seems as simple, at least to me, as it has scratched and chipped in a random, ridiculous fashion so it must not be the quartzite that we paid thousands of dollars for because quartzite does not do that.


    Where am I wrong?



  • Jenny
    6 years ago
    Hi @karin_mt!!

    Hi guys, going to post in a few places because I’m feeling a little confused/unsure. I got 2 samples of super white quartzite and tried testing them. The one that was sealed etched like crazy and the one that was unsealed looks totally fine. Is it just that they are different slabs? Or is it possible that it’s the sealer that got etched? Is that even a thing? Did any stone fabricators allow you to get a sample of your specific slab to test it before you 100% committing to it? Not sure where to go from here.
  • karin_mt
    Original Author
    6 years ago

    Hi Jenny,

    Well, that doesn't make sense. But it also doesn't matter that much. Super White isn't quartzite and it will etch, regardless of sealers. Some parts of it may etch more slowly, but it will still etch.

    Super White is dolomitic marble, not quartzite. Dolomitic marble etches a little more slowly than regular marble.


    As for getting a sample of your actual slab, that seems a little unlikely, but certainly worth asking. You'll probably have better odds of getting a sample from the same batch, but a remnant or scrap from a previous job.


  • zyoyomama
    5 years ago

    Hi all-


    Redoing the kitchen and found a great slab of rock at local store for my kitchen island. They gave me a great deal on it because there were some slight imperfections, but since I will be putting a cook top on this slab, the fabricator can cut out the imperfection. My husband and I both fell in love with this rock.

    Rock is paid for and delivered to the fabricator for cutting. I went back to match the slab to a more simple quartz to do the surrounding countertops, and the sales lady said this could be either marble or quartzite. I am nervous because I know how finicky marble can be. It is called "Picasso", but after doing more research, it can be either quartzite or marble. How complicated and confusing!

    I'm planning on having the slab sealed prior professionally once it is installed. If it is marble, and I guess I won't find out until its installed, what can I do to make sure I keep this rock in the best shape?

    Thanks!

  • karin_mt
    Original Author
    5 years ago

    You can find out what it is! No need to guess or wait. Do the tests, check the hardness with a knife, somewhere on the edge of the slab.

    Read this for more info.
    http://usenaturalstone.com/definitive-guide-quartzite/



  • zyoyomama
    5 years ago

    Interesting update- it seems the slab of rock has both marble and quartzite, as some areas etch glass and some leave a talc residual behind. We are going to have is professionally sealed and treat it like marble.


    Thanks for the help!

  • PRO
    MaryAnn Korman
    2 years ago

    I am so confused. So, is it a good thing if the glass scratches when you drag it across Quartzsite? Do you recommend Quartzsite over quartz?

  • karin_mt
    Original Author
    2 years ago

    Oldryder's advice is worth wayyyyyy more than 2 cents! Well said.