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ADVICE WANTED!   July 31, 2002
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Other Characteristics - General

Physical, chemical, technical characteristics of other in general

  General, Marble, Granite, Limestone, sandstone, Travertine
  other, bluestone, slate, onyx, engineered stone, manufacture stone, basalt, pebbles, flagstone, lava

Q 2304: In your response to a question that read "Does anyone have any particular do/don'ts when dealing with un-gauged Indian Slate? Dave, March 4." You responded "don't". Would you expand on that short answer please? I have also considered 12" gauged multicolored slate for kitchen, entry, hallway, but don't care to make an expensive mistake. What is your opinion of china white / gold quartzite? Thanks-much!! Leslie, July 26,

Q 2244: Does anyone have empirical information (or even an opinion) regarding the comparative heat resistance of granite and "manufactured stone" (such as zodiaq and Silestone)? Because I would wanted a very light colored countertop, I was leaning towards manufactured stone. I read, however, something that suggested that manufactured stone shouldn't be used as a regular "landing pad" for stuff coming out of the oven. Marianne, July 16.
R1: Dear Marianne: Whoever told you that was right. The approximately 6% of resin in engineered stone (which is the bonding agent of the quartz chips) could be damage by the 
heat of a pot.
Now, about this thing that light colored "granite" is usually bad as far as maintenance is concerned> True geological granite is either white, or light gray, or pinkish, and its porosity is quite controllable with a good quality sealer! are those color light enough for you? Check the "Bianco Sardo" granite (a.k.a. "Luna Pearl"). It's a great stone! Maurizio, USA
Q 2178: I would be grateful for advice on what method I should adopt to get a marble effect on slate, I am aware that the slate has to be painted black to begin with, but after that, what product/method and tools should I use to obtain the best result. Barry, July 8,
R1: Dear Barry: I must know something that I don't know! In fact, unlike you, I'm not aware that slate has to be painted black. I actually never heard of such a silly thing! And what about getting "the marble effect"? I really wish I knew what you're talking about!! Ciao and good luck, Maurizio, USA
A 2144: Can you give me some information about zodiaq, its pro and cons? Maria, June 30, .
R1: Dear Maria: "zodiaq" is a so-called engineered stone. It's manmade by mixing quartz crystals (94%, I believe to remember) with epoxy resin (the reminder 6%). If you like the way it looks, there are not many cons I can think of. Ciao and good luck, Maurizio, USA
A 1952: We purchased some onyx wine glasses and the sales rep said they were unsafe to drink from. Can you advise? Vicky, May 22,
R2: Dear Vicki: The safety aspect really depends on what you are drinking, how much, and
with whom. I presume that you are referring to onyx marble rather than onyx which is a semi-precious variety of agate used for the manufactures of cameos, rings, cuff-links (showing my age), and intaglios. The name onyx has been used historically for a number of rock types including alabaster, marble and chalcedony. Assuming that yours are onyx marble the main danger is to your glasses rather than to you because of the reaction between marble and anything acidic. Wine is acidic and will etch the marble (partly dissolve it). In doing so it will necessarily leach into the wine any substances that might be contained within the marble. Simply avoid drinking from these glasses unless it is pH neutral water. (Dr. Hans), Australia
R1: Vicky: Wow, two salespeople in a row that are right!! That's a first all right! Wine is acidic (acetic acid) and will corrode all calcite-based stones, Onyx among them and first of all! Do NOT pour wine in those things of beauty! It won't do your health any harm, but it will alter the taste of the wine while slowly destroying the stone. Maurizio, USA
A 1913: Hi! Where can I find info and facts about basalt rocks for a science project? Thanks, Angel, May 16,
R1: Dear Angel: Be an angel and get off your backside and look up some books that contain information about the most widespread and common rock on this earth (and the Moon). There would literally be many millions of pages written about basalt! (Dr. Hans) 
A 1708: I saw a picture of the industrial & Commercial bank of China in Shanghai Very curious to know what effect can Onyx create to the bank ? What finishes to use on Onyx to make the wall lively? Patricia, April 14.
R1: Dear Patricia: What do you mean with "What finish to use on Onyx to make the walls lively?" Onyx, like any other stone that can be polished, is polished by abrasion and friction, not by putting some sort of finish onto it. Of course, like any other Calcite-based stone it's very sensitive to pH active chemicals, including rain, pollutants, etc., therefore it is certainly NOT a stone that you want to consider installing outdoors. 
Talking about China, I am personally consulting with the company in charge of maintenance of the new head quarters of the Bank of China in Beijing. They finished the building over two years ago, but it still not occupied. They cladded all the outside walls with polished Italian Travertine. A stone like that, much as Onyx, can't be used outdoors, so I went to the trouble of formulating a special sealer -- both penetrating and topical -- to help minimize and delay the damages that the exposure to the weather will produce eventually. In over two years, they never reached a decision, and, by now, the whole thing is already in need of a serious restoration procedure. Considering the size of the walls (close to 200,000 square feet. No it's not a typo!), the technical difficulties attached to the project and -- most importantly -- the glacied pace to which the Chinese Bureaucracy moves, I can only envision one big mess! But, hey, I'm still on! Ciao, Maurizio
A 1575: My name is Michelle & I am an interior decoration student in Sydney, Australia. I have been asked to research pebbles. I need to find out - history, properties, UV light effect, slip resistance, effect from oils, effect from acids etc. strength, maintenance, fire resistance. March 21.  
R1: Michelle, LOL there are so many different types of pebbles that you basically can't get a response. You need to narrow your research down to specific types of pebbles with specific properties first. Write back for help when you have narrowed your request down. Steven, USA 
R2: Dear Gwen.. Sandstone is a geologic term describing a particular type of stone, i.e.. a sedimentary stone composed primarily of sand (quartz) sized grains. The amount and type of inter grain cementing materials determines the density and relative hardness of the stone. Flagstone is a descriptive term referring to stone that is relatively flat on both surfaces with a uniform thickness that breaks into random shapes. Any sedimentary stone can be a flagstone if it was deposited in thin, distinct layers with a definite break in the deposition between the layers. I have seen both sandstone, and siltstone flagging from OK., and limestone is often found as a flagstone type. JVC, USA,
R1: They could be. Yes there is sandstone in Oklahoma. Regards, Steven, USA
A 1476: Please tell me the difference between Slate tile and Quartzite tile, if any and which would cost more. Thank you. Harold, USA, Feb 27.  
R1: The primary difference is mineral composition and physical make up. The cost is relative to where you are and what is available. In my part of the country they are pretty equal in cost. Regards, Steven, USA,
A 1301: What are the costs/benefits of granite vs. silestone? I know that granite's beauty is incomparable, but I am concerned about staining and susceptibility to heat. I have read that silestone is great, but can be manufactured in sheets no longer than 10, so there are problems with seams. Donna, USA, Jan 5.
R3: From the perspective you are viewing this both materials could work for you. The natural stone would need to checked for absorbency. Many stones don't absorb very much. Susceptibility to heat affects some of the darker engineered stones so give that vote to natural stone. Cost wise engineered stone is less expensive to begin with. So you are left with aesthetics and your willingness to investigate natural stone. On this forum, we would like for you to personally check the absorbency of the stone by conducting Maurizio's now infamous lemon juice test. Scroll through previous answers to find it. Best regards, Steven, USA,
R2: Dear Donna: It's impossible to answer your question with black and white statements. There are too many grey areas. Engineered stones (and Silestone among them) are only relatively less expensive than "granite" (approx. $5 per square foot), therefore price is hardly a motivation to choose a material over the other one. The advantage with engineered stones is that are more predictable, as far as maintenance is concerned. In fact, "granite" is much more unpredicatable, due to the fact that the vast majority of the stones traded as granite are not granite by a long shot. What's more important, is the fact that the vast majority of the stone fabrication facilities' operators are just as "intelligent" about "granite" as you are. In fact, they've got their stone education from a whole army of salesmen and the importer/distributor's invoices. Most of them don't even know that what they sell as granite is not, in fact, granite. Hence, all the confusion and the different hearsay about "granite" countertop. Some end-users are delighted, some others, at the other end of the spectrum, are just about ready-to-kill-the-who-sold-granite-to-them. What's my advice? I'm too much in love with natural stone to encourage you to buy something else, but I do understand your concerns (by the way, "granite" is way more heat resistance than engineered stone). I devised a little test ("the lemon just test") that anybody can run, and that you can find somewhere else in this site, which helps a lot at narrowing down the selection of natural stone. When shopping around, do NOT listen to anybody: just run the test and rely on it. It's honest and unbiased. Ciao, good luck, and have fun in the process, Maurizio, USA,
R1: Your observations are correct. Granite is a natural stone and has its own character. Like all natural stones, it has its own beauty but with it comes some of the defects (not all materials made by God are perfect). Sometimes we try and cure most of the defects to enable the stone to perform equal to manmade stones. Manmade stones are mere agglomerates of stone chips/powder in resins/binders and then cast into sheets. You can compare it with pre-cast concrete where stone aggregates mixed with cement is cast. Silestone will give you an impervious surface but will not have the natural look. It will be like synthetic leather v/s original leather. Arun, India,

A 1124: I have a number  of clients asking about?? Pyroclastic Lava. Could you tell me about the product in relation to use in countertops. I remember it as glass-like porous material from Geology classes. Thanks, USA, Oct 5.  

R1: "Pyroclastic lava" makes no sense. There are products of lava flows or pyroclastic flows. Lava flow products examples are basalt, andezite, rhyolite. Pyroclastic flow products examples are tuff, welded tuff or volcanic Breccia. Some porous basalts are named lava stones. There are not suitable for countertops without sealing. They are not polishable, They are mainly of black to dark grey colors. Daniel, Slovakia,
A 1109: I am a research student looking for relevant information on serpentine. Ty, USA, Sept 24,
R1: Serpentine is usually dark green, veined, often brecciated, metamorphic rock which was formed from upper mantle peridotite rocks during collision of lithospheric plates. It is created from serpentinite and small amount of calcite, magnetite, chromite and pyroxene. The hardness of serpentinite is similar to marbles, but it is chemically more stable. Daniel, Slovakia

A 1087: I am trying to find a product called bluestone. I don't know if it is granite, marble or limestone. Please advise. Angela, USA, Sept. 2,
R6: Bluestone is not marble granite or limestone - it describes a type of stone that is not easily cut to a specified dimension.  Flagstones can be described as bluestone as they are used as irregular shape slabs often in the shape that they are extracted from the ground.  The opposite of bluestone is "free stone" or "dimension stone", such as sandstone and marble that can be freely cut to size. Regards, Jim, Australia,

R5: It is a stone similar in properties to slate. Domestic varieties come from Pennsylvania, New York and North Carolina. Steven, USA.

R4: Bluestone is a name for sandstone that is quarried in NJ and PA. You should be able to find it at most stone suppliers. Fred, USA

Unfortunately for you, bluestone is a loose term in the stone trade meaning different things in different countries.  Even in the same country, bluestone can vary dramatically in composition and appearance.  For example, in Australia, bluestone is a basalt in Victoria and used mainly for paving; a volcanogenic greywacke (sandstone) in Queensland; and an impure, fine sandstone that has been metamorphosed to a low grade, in South Australia. The South Australian bluestone is similar to the Italian Cardoso stone. So what you have to do is find out what the specifiers of your American stone mean by bluestone. Hans, Australia,

R2: Bluestone is a sedimentary/ metamorphic stone. In the United States, it is quarried in south central New York and northern Pennsylvania. It has many of the qualities of slate like a natural cleft, and have color variations too that are beautiful. You may know it as "Flagstone". It is used for patios, sidewalks, and for veneer on basements and chimneys. Burzin, India.

R1: It is not granite, it is not marble, its not limestone either. Amazingly, it is ... Well, Bluestone! Large quantities can be found in Pennsylvania. Ciao. Maurizio, USA,

A 1019: As we are considering to import and distribute slate for roof covering, I am missing lab tests regarding content of Calcium carbonate (lime) which has a negative effect on the quality of slate. Also, some types of slate are difficult to cut/form. Could you please direct me how to find guidelines about the various quality characteristics for slate? Bjorn, USA. June 21 reply
R1: A good starting point is the established ASTM test methods as follows:
    ASTM C120 - Flexure testing of slate
    ASTM C121 Water Absorption of slate
    ASTM C217 - Weather Resistance of slate
Jim Man, Australia Contact