Material Characteristics

 

Inquirers: Experts will answer your questions and solve your problems. So email your question for free display here. If you are willing to pay for some specific service or want to buy some specific type of product, do state so.
 
Advisors: Please share your knowledge and expertise and give as detailed a reply as possible to each inquiry. If you can offer some specific service or product, please mention the type of service or the generic product-type with indicative prices. If you can email us a detailed list of products and services, we will give it as a separate link.

---

A 1394: I'm interested in finding a Los Angeles or Orange County company that sells Basaltina Granite. Also, would like to know if it is appropriate for a kitchen countertop. Cathy, Jan 31. Reply

R1: Dear Cathy: "Basaltina" is not a granite by a long shot. In Fact, it doesn't even pretend to be one. It's a volcanic stone called Basalt (hence the name Basaltina) and is quarried in the proximity of Rome, Italy.  That said, you do NOT want to find out if anybody in Orange County, CA carries it. In fact, you want to stay as far away from it as possible (as a material for kitchen countertop). Too darn absorbent! No sealer can do a perfect and decently lasting job while dealing with such a degree of absorbency. Ciao and good luck, Maurizio, USA, Expert Panelist. Reply

R3: The cracks will eventually run through and crack the top. You may use a polyester resin to fill out the cracks. The resin will hve to be suitably pigmented to match colour and then the top will have to be refinished to remove excess resin leftovers. Regards  Arun, India, Expert Panelist, Reply

R2: Karen, Maybe it can be repaired, maybe not. look in your yellow pages for a granite and marble fabricator, and have them check it out. They will probably want to rod the back in addition to the glue work. There are glues formulated for this kind of work, and coloring agents to add to the glue (epoxy or polyester). Good luck JVC, USA, Expert Panelist. Reply

R1: This is not a repair I would like you to carry out. If the piece has a number of veins in it then I believe a good fabrication facility could repair it for you where it won't be quite so noticeable. If it does not have a lot of veins then I believe it can still be repaired but you will see the line. Regards, Steven, USA, Expert Panelist. Reply

A 1390: I noticed that you seem to have a lot of information about the wear and care of limestone. What do you know about Bulgarian white and yellow limestone and would you recommend it for use in a formal entryway? How soon would it begin to turn black from regular footstep traffic? Also do you know anything about Antique Blanc Rose and how practical that would be for a kitchen application -just looking at it makes you wonder how you clean it? Rachel, Jan 30. Reply

R1: Dear Rachel: I don't know the first thing about those Bulgarian limestone. Generally speaking I always encourage people to stay away from limestone, but then, this is just a general suggestion. What I do know for sure, however, is the you do NOT want Antique Blanc Rose in your kitchen floor!! (unless, of course, you're kitchen is going to be only some sort of show-place!). Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

I would really appreciate your opinion on whether Antique Blanc Rose would be the right choice for a kitchen floor. Supposedly it is a hand made cooked stone that is over 100 years old salvaged from the South of France. Have you any experience with this stone? Rachel, Reply

Dear Rachel: I already answered your questions, didn't I? I repeat, I don't know the first thing about those two limestone. Nor I care to know. Just because they are limestone, I don't like them already! No limestone will ever find its way inside my house, and the same principle applies to Antique Blanc Rose, despite the impressiveness of the name!  Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

A 1384: What do you know about Bulgarian white and yellow limestone for usage in a formal hallway? Also what information can you share about Antique Blanc Rose for usage on a kitchen floor? I am interested in how you clean and maintain these floors? I am also wondering about the usage of the Antique Blanc Rose? Rachel, Jan 28, Reply

R3: Dear Rachel: If you ask me, cleaning that floor wouldn't be a problem: a good clean mop with a solution of water and a stone detergent (NOT a stone soap). The real problem will be represented by the removal of all the stains that you will eventually be getting, no matter how well you're going to have that stone sealed, even if the contractor uses the "Seal-all" impregnator made by the "Bestest" company. Ciao and good luck, Maurizio, USA, Expert Panelist. Reply

R2: Hi Rachel , limestone is absorbent. You can clean with a stiff hand brush and a cleaning agent. Wet dry brush sparingly. Do not create a puddle with the sealer. Always do a sample first. John, USA, Expert Panelist. Reply

R1: Dear Rachel, the name for Bulgarian limestone is VRATZA. It is used for years in our country. It is suitable for floor because of its pleasant color, stability, but after some time, it is difficult to remove dirt from surface from its filled pores. ANTIQUE BLANC ROSE is French type of terracotta. Daniel, Slovakia, Expert Panelist. Reply

Thank you for your prompt response to my questions regarding Bulgarian Limestone. How would you remove the dirt from the filled pores -is it a complicated operation requiring professional cleaners or could you clean it by yourself with what cleanser? Does it require a "sealer" and what type would you recommend. How porous or absorbent is this stone? I thank you for taking the time to answer these questions. Rachel, Jan 29. Reply

Thank you for your prompt response regarding Bulgarian Limestone. You mentioned that dirt would have to be cleaned from time to time from filled pores. Are you referring to professional machine cleaning -or can it be maintained for a reasonable period of time through home cleaning methods. Should this stone be sealed and would you have any information on what type of sealer. Also, what do you think about the maintenance of Antique Blanc Rose on a Kitchen Floor. Is it at all cleanable or practical? I appreciate your time and expertise, Rachel Reply

Dear Rachel, excuse me I am not expert for stone maintenance and using of terracotta. I can only say, that in my university the floors have been from Vratza limestone for over 20 years. Pores are filled by dirt. The floors were not cleaned by special technics or chemicals. Maybe other expert will advice you. Daniel, Slovakia, Expert Panelist. Reply

A 1348: We will be remodeling our kitchen on the coast in Florida. We have been receiving conflicting information from three different sources (three separate opinions). I need a definitive answer: CAN YOU PUT A HOT POT ONTO A GRANITE COUNTER TOP.... I am very frustrated. A company that specializes in granite counter tops (and marble) told me that it requires more care than the synthetic tops like Wilsonart and Corian (?). I talked to the designer at Lowes and he told me that it didn't take as much care and that you COULD put hot pots off the stove. Would you please tell me the strait scoop on granite counter tops? Even on the internet I got two different opinions from two vendors. 1. Will granite stain like Wilsonart? 2. Will it crack from heat (example: pots from stove)? 3. Will it scratch easily? 4. What is the average cost per square foot, installed in the south eastern states? Any help you can give would be most appreciated.  Thank you Faye, Jan 18. Reply

R3: Dear Faye: If it can be of any consolation, the good news is that lack of professionalism is not limited to central Florida, but all over the country and beyond!  What to do?  Well, not much for the time being. For starters, it seems to me that the recognized authorities of the stone industry have, as their main goal, to promote the use of stone (to sell more and more of it, that is), but don't care much about business ethics and intelligence. In an environment where there's no official guidance and precise definitions and guidelines, it's hard to expect salespeople to become experts on their own!!  To have educated people you need good certified teachers. In this industry any quack with something to sell can go on stage, grab the microphone, and say that he or she knows everything about stone, and then some!! What else can I say? It's sad, but that's the way it is. Ciao, I'm upset, Maurizio, USA, Expert Panelist, Reply

R2: Hello Faye, All the answers you have received are confusing.  Starting from the bottom budget about 75-80 USD per a square foot for allowance. With regards to heat it is always prudent to test things. Granite started its existence in a flowing state then cooled. The temperatures to melt granite are so much higher than any man made product it doesn't really bear discussion.  I have taken hot pots and put them on my countertop without incident. I think that if you get a low absorption stone ( use the lemon slice test devised my Maurizio - a good expert on this site) and test each piece of stone your self. All the sales people are telling you things that are correct in specific contexts. The contexts are the following-- 1) Many stones get called granite that are not. The swirly juparanos and many of the really light stones are not granite. If you put them (light & swirly) in the kitchen you will have to be very diligent about wiping things up as they occur and use trivets for hot things. Many people do not clean as they go and they forget the trivets. This will lead to problems. 2) Many people are attracted to stones with veins or fractures. Veins and fractures typically are the weakest point in a stone. So back to the stone versus the hot pot question. If you ever touch a piece of stone you will find that it is quite cool. So if you take something really hot and place it on something cool you will have a rapid thermal change in both items. Rapid thermal change causes stress. If the rapid thermal change is near a fracture then it can cause it to crack. So, if there are not any fractures near the point you put the hot pot you should be fine.  3) On the Mohs scale most kitchen knives fall between a 4 and a 5 for hardness. The granites are usually a 6 or a 7. Therefore you should expect the knfe to dull rather than the stone to cut. But don't trust a sales person, ask for a sample of stone you like. Put hot stuff on it to see if the shine is harmed and the stone is affected, try and scratch it with a knife, put a slice of lemon on it for a minute then take it off. See how fast the stone gets wet. If it greater than two minutes you are in good shape. Sorry to be longwinded, Regards, Steven, USA, Expert Panelist, Reply

R1: Dear Faye: 1. I don't know how Wilsonart stains. I do know that "granite" will stain if you select the wrong "granite". Go with my "lemon juice test" - it's very dependable.  2. Most likely it won't crack from heat (I do that all the time on my own top!), but, if it's a "granite" that need sealing, the heat will damage the sealer. You don't want that!  3. No, granite doesn't scratch easy at all, but "granite" might (never so easy, anyway). While doing the "lemon juice test" on pieces of scraps try to scratch them with the tip of a knife and be the judge.  4. I live in NJ, I don't know. Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

A 1332: I am in the process of evaluating marble for usage in the flooring of my apartment. Have got variable inputs from various dealers. Some suggest that the Indo Italian marble, though better in looks and texture, is very soft and could wear out pretty soon compared to the Indian Makhrana White marble. Needed some technical assistance on this issue. Rajshekaran, India, Jan 15. Reply

R2: Dear Rajasekharan:  First off, I don't quite understand the meaning of Indo Italian, but I guess that you're making reference to the all the types of marble coming from Italy that are known there in your country as "Italian marble". Your dealer is right and wrong at the same time. Wrong, because under the classification of "Italian marbles" there is a huge variety of stones, processed in Italy, but coming from all over the world; therefore, most of them are, in fact, harder than the Indian Makhrana. He is right, however, in stating that the Indian marble (that, in fact, is a dolomitic stone) would be easier to maintain. First off, its chemistry makes it more resistant to chemical alterations than most "Italian marbles". Second, It typically doesn't come so highly polished. I personally love that stone! If memory serves me right, that's what the Taj Mahal is made of!  Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

R1: Dear Mr. Rajasekharan, It is very difficult to compare the two qualities of Marble you have chosen. Indo-Italian is a fine marble BUT is soft as already suggested to you, whereas Makrana Marble is much harder and gives a better life. You may have difficulty in selecting the Makrana Marble of your choice as I believe you are looking for a white marble with minimum black coloration / stripes. I would suggest that you go for a Makrana Marble for a longer life but please do not compromise on the aesthetics. A house is made only once in a lifetime. Even very soft marble can be hardened using chemicals and (most of the Italian Marble slabs are resin impregnated). Feel free to select the stone and we are there to help you in providing the necessary materials/chemicals to make the stone usable and to give a good life. Regards Arun, India, Expert Panelist, Reply

A 1318: I am trying to locate a resource which can provide the Absorption Percentage for Carrara Marble. If there is a range of absorption rates I am interested in the Lighter of the Carrara Marble. We are interested in lining a Baptismal Font with the stone, however can not confirm that the material properties of Carrara are suitable. Thank you for any information you can provide. Jonathan, Architect. Jan 10. Reply

R2: I cannot provide you with the information on the absorption rate of Carrara Marble. However, I can provide you with information on the application of the Waterproof Membrane in the font. Art, USA, Expert Panelist. Reply

R1: Dear Jonathan: It's not as much the rate of absorbency of the White Carrara marble that you should be concerned about (it could be easily controlled with a good-quality impregnator sealer), but its chemical makeup. There's quite a bit of iron mineral within this particular type of stone, and if for any chance the water finds its way (even slightly) behind it (through the seams), it will turn yellow because of the consequent oxidation of the iron (rust). Many a white marble have inherently that problem. I would advise to reconsider the color. Ciao and good luck, Maurizio, USA, Expert Panelist. Reply

A 1288: Which class of marble is Perlato Sicilia? Nikesh, Nepal, Jan 1. Reply

R1: "Perlato Sicilia", "Perlato Royal" (the latter allegedly being a better selection) is a compact limestone that's quarried in the island of Sicily, Italy. It's very hard and dense, it takes a very high polish, and shows several fossiles throughout its texture. It's usually a class "B" (at best), or "C" marble. On a personal note I love that stone. Too bad that in the past 6 or 7 years it went out of fashion here in the USA (at least in the North East). Ciao, Maurizio, USA, Expert Panelist, Reply

A 1287: I hear from some people that Texas (cream) limestone won't stand up to freeze / thaw conditions as well as Indiana limestone. Is this true? Also, which ASTM test results do I look at to determine how well a stone will survive in my mountainous Virginia climate. John, USA, Dec 31. Reply

R3: Water absorption is the most basic physical property and also the most useful. It can also be used as a rule of thumb for freeze / thaw resistance - the lower the water absorption, the higher the freeze / thaw resistance. Jim, Australia, Expert Panelist. Reply

R2: John.. Texas Creme Limestone has been used all over the country, Canada, and over seas for more than 100 years now. It will hold up in your climate about as well as any limestone. The truth of the matter is that no porous stone will pass ASTM freeze-thaw test as the testing is done on stone that is saturated with water, which should never be the case with stone installed in a vertical situation on a wall. If you are considering the stone for architectural elements in a building, Texas stone will work just as well as any other. If you are considering using the stone for flat work, ie patio or staircase than you might run into a problem. Finally, whatever stone you choose, please consider sealing with a good, breathable sealer to limit the amount of moisture entering the stone. Texas cream is softer than the Indiana stone, but it also has a warmer, distinctive look to it that the Indiana stone does not have. JVC, USA, Expert Panelist. Reply

R1: John, while it is true that Texas Creme limestone is not as stiff and dense as the Indiana limestone, it has been used successively for exterior applications in many cold climate areas. What is the application you are considering? Are you going to use the material for flat work (Patio or stairs), unprotected wall cap, or for veneer or other architectural features? The application would make a difference, Also, no matter what stone you choose, plan on using a breathable sealer to limit the amount of moisture gaining access to the stone, as all pourous stones are susceptible to freeze thaw damage if water is allowed to saturate the material. JVC, USA, Expert Panelist. Reply

A 1283: I am looking for the physical properties of Absolute Black. Can you please help me with this? Steve. Dec 24. Reply

R1: Dear Steve: There too many stone traded as "Absolute Black" (none of which a granite) that are so much far apart from each other from a physical and chemical point of view to enable anyone answering your question in 2,500 worlds or less. Suffice it to know that the majority of them are very dense and hard stones and make a terrific material for a kitchen countertop. Maybe our friends Daniel and Hal will be more precise then me on this one: their knowledge of stone from the inside out is just about "scary"! Ciao, Maurizio, USA, Expert Panelist, Reply

A 1276: Referring to 1270, thank you for for remarks. What is the difference between serpentine and orphicalcite green marble? I just know I saw here in Belgium in a showroom some very nice tile, a little bit translucent green marble with no white veins, called Rajasthan green, I think most looking like Imperial Green on the website of FindStone. As I go again to Rajasthan for holidays, I think to look myself by producers of green marble. Do you think you can combine marble with sandstone in one floor 40 x40 green, with little red stone in the corner of 4 green stones? Any comment is welcome. Marc, Belgium, Dec 22. Reply

R1: Dear Marc: You're really serious about getting in the stone business, aren't you! Well, welcome and good luck, my friend. I wish you the best! Most green marble are serpentine (Magnesium Silicate). The only green ophicalcite I know of is the Italian "Verde Alpi", but there maybe more. The main component is still serpentine, with the addition of gabbro and calcite. Ophicalcite can come in a color different than green, i.e.: Rosso Levanto, Cipollino, and the Valle D'Aosta so-called "Onyx of Chatillon". Ciao, Maurizio, USA, Expert Panelist. Reply

A 1273: What is the weight per cubic foot of sandstone? What is its hardness? Thanks, Bob Dec 19. Reply

R2: Bob, There are too many variables in effect to give one specific answer. Weight per cubic foot depends on mineral content, grain size and sorting (compactness), and the inter grain cementing material. A loosely cemented (friable) calcareous sandstone may be on the order of 130-140 lbs / cubic foot, while a well sorted, densely packed, silicate cemented stone could be in the 180 lb range. Hardness of the stone also depends on these same variables. Some can be scratched with your fingernail, while others give diamond saw blades a good workout. Again this depends on how well the little grains of sand that make up the stone are cemented together, and by what. And finally, as a carver, I need to consider the fact that the predominate material in a sandstone is quartz sand, a silicate mineral with a hardness of 7, while good tool steel has a hardness of about 5.6, which means the sandstone is going to be hard on my favorite chisels, and as a silicate, hard on my lungs. Hope I haven't confused you too much. JVC, USA, Expert Panelist, Reply

R1: Sandstone typically weighs 120 -140 pounds per cubic foot depending on the grade. The hardness is more difficult to evaluate as it depends on what scale you want to use. Most people know of Moh's scale, but it isn't much use on friable sandstones as it is difficult to see a true scratch. There are other true hardness methods such as Knoop and Brinell hardness that give an overall hardness but these are very specialized. Measuring hardness by determining its abrasion resistance is the most universal method via ASTM C1353 "Abrasion Resistance of Dimension Stone Subjected to Foot Traffic". Using this method, sandstone has a typical abrasive index from 2 to 18 with anything less than 8 not really suitable to for paving. Regards Jim, Australia, Expert Panelist, Reply

A 1269: Whilst Black Galaxy does not pit as much as Jet Black, it appears there are a few pits or chips in a kitchen top recently installed that I have viewed. What can cause this to happen? Is it the mica spots falling out, or is it water exploding them off or was this likely to be in poor polishing of slabs. Some pits are more like chips approx 3 to 5 mm in size. Is this common for Black Galaxy? or Should the top be perfect without any pits or chips at all. Over 8 to 10m2 there would be say 20 or so pits or chips, with most needing light to show them up, but some are quite evident. Is this something that can be fixed, if so, How? Your urgent reply will be appreciated. Michael. Dec 18. Reply

R2: Michael, As Black Galaxy is not technically a granite it is usually not prone to pitting. That said there are many grades to materials and you may have one that is pitted. The problem with telling you to fill them is that Black Galaxy typically has a very high gloss. You are noticing pits that takes some light at a particular angle to see. My thought is you would see any resin or schelack that I would instruct a professional to use. This would help with feeling the pits though. Please decide what is the most important aspect, seeing the pits or feeling the pits, before you proceed. Best regards Steven, USA, Expert Panelist, Reply

R1: Dear Michael: I don't even know if there's any Mica in Black Galaxy. In fact it's a gabbro, not a granite. Regardless, if you want to know what caused that pitting you should inquire with the "Man upstairs". Simply put, you're looking at some poor grade slabs. Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

A 1261: I too have been trying to find information (similar to that of A1248) for 3 weeks and have been unsuccessful in locating any information regarding flame retardency or sound absorption of granite. If you have any information on these two areas, or know where I might be able to find information, I would really appreciate it if you could help me in any way. Thanks, Tripti. Dec 14. Reply

A 1252: I need information on Corinthian Granite. Cliff, Dec 11. Reply

A 1248: I am doing a paper on granite for my materials and sources class. I need to know the following on  granite: Pollution Resistance (Air and Chemical Exposure), Flame retardancy & Toxic Factor (smoke), Sound Absorption. Also, if you are using grout to install granite--what type would you use and why would you use it? My paper is due on December 14th.  Any help you could provide would be most appreciated. I will be sure to send the paper to you when I am done. I LOVE YOUR SITE!!!!!!! :-) Thanking you in advance for your assistance. :-) Nafisa, Dec 10. Reply

R2: You know that I do believe in being as polite to all of our people who ask questions; but I dislike it when students procrastinate with their projects to the point of asking us to do their research for them. Further I would have to write a treatise to even answer this one. Poorly done. Regards, Steven, USA, Expert Panelist, Reply

R1: I would recommend an epoxy grout or a portland cement based grout. Regards, Steven, USA, Expert Panelist, Reply

A 1238: We are producers of marble in India. Our problem is that our material has high porosity and so it doesn't hold good polish and looks very dull even after polish. Is there a way to reduce the porosity so that it holds good polish as we find marketing our slabs difficult? It is lime stone and very soft by nature. Ganesh, India,  Dec 5. Reply.

R4: Well now.  quarrying a limestone, but want to sell a marble. I'm sure that you can find some way to make your stone appear to be denser, harder, and less porous than it actually is.  Rather deceptive, but then ethics in business seem to be fading these days.  A  successful business is built on repeat business, and even if you can find a way to alter the appearance of your slabs, it is not going to last through the fabrication process, and the end user is going to be upset.  Read some of the postings on this website.  Market your stone for what it is.  If it is a good limestone, with consistent color and character, you will find a market for it.  How large can you quarry blocks?  Are they clear, or is the stone full of dries?  Is it carvable?  Does it work well with machines such as planers and lathes?  This market is full of "marbles" that aren't marble, and "granites" that aren't granite, and all that it does is confuse the consumer, and create massive headaches for us in the fabrication end of the trade.  Think well about what you are trying to do. JVC, USA, Expert Panelist. Reply

R3: Dear Ganesh, There are a range of epoxy sealer for marble reinforcement and therefore will help to strengthen the porous marble during polishing. The epoxy sealer works by penetrating deep into the vein. cracks, etc. It will enhance the gloss after polishing. Regards. Soh, Malaysia. Reply

R2: Dear Ganesh: Either a stone is crystallized enough and will polish, or it isn't, and won't polish. Case in point, many a limestone won't polish, no matter what you try to do to them. So, unless you can find someone who can do a better job than Mother Nature herself, you're going to have to learn how to live with your stone the way it is, and try to sell it for what it actually is, rather than seeking ways to cheat Mother Nature, and, ultimately, the final consumers of that stone. After all, the market is already full of unpolished limestone and they sell quite well.  If this can be of assistance, in the furniture business some manufacturers coat stone (marble, or what-have-you) with shellac, after acid-washing the surface to rough it up and assure a better bondage. The final result -- although plastic-looking -- is very shiny. Ciao and good luck, Maurizio, USA, Expert Panelist. Reply

R1: Hi! I would cover it with concrete base grout (non sanded) like travertine between the first grind and all the rest. Pini, USA, Expert Panelist. Reply

A 1237: I must openly admit to you that I am no bag of money, working on little more than a whim or sudden fancy.  However, if you have time to satisfy my curiosity, please answer my questions. I have recently been informed of Pentalic Marble, and how it beautifully changes color as the sun's light shifts.  I do not see this stone on your site. What other stones have these properties?  How much do they cost (I leave the unit of purchase to your greater experience)? Ian, Dec 4, Reply

R1: The only marble I know is Pentalic marble. This is a native Greek marble that buildings like the Parthenon are built from. As for changing colors, I have never heard of it doing that. Best regards, Steven, USA, Expert Panelist. Reply

Steven: Pentalic marble does not change color itself, like a chameleon, but it is particularly apt at reflecting different shades of sunlight for the most beautiful result. Ian

A 1226: I am interested in general info- flooring, walls, counters. I am a kitchen and bath designer and national educator for the industry, so will use the info for projects and to spread the word- images are great! I recently was told by a supplier that it is possible to heat the walls using radiant heat if the tiles are set in mud. This was then challenged by a solid surface supplier who said that any adhesive is destroyed by the heat. I'm thinking mud or concrete is ok with the heat. What can you tell me about this? Mary Jo. Nov 26. Reply

R2: Dear Mary Jo: The solid surface supplier is dead wrong. Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

R1: Solid surface materials are usually plastics. They have a lower thermal tolerance for their composites. Stones and tiles set in cementious materials should be no problem. Best regards, Steven, USA, Expert Panelist, Reply

A 1203: Can you help me? I would like to know general characteristics about Rosa Levante and Rosa Gerona marbles: are those marbles or limestones? What's their colour and if they presents a large variability of colours, what are their exact locations, why Rosa Gerona got this name if it isn't from Gerona?, about their fossil contents, and about their geological age, if it's possible. I'll be really grateful if you can answer about it. Many thanks, Marta, Spain, Nov 21. Reply

A 1178: We are looking for information on Ceasar stone. Can you help us? Donna, Nov 10. Reply

R2: Dear Donna, Caesar stone is quartz-based artificial stone from Israel. Daniel, Slovakia, Expert Panelist. Reply

R1: Donna, Caesar stone is an engineered quartz product. It has the hardness of granite. It has more flexibility than granite. It is not necessarily as shiny or heat resistant as granite. It is less porous. It is approximately 10% less expensive than granite. Best regards, Steven, USA, Expert Panelist. Reply

A 1176: Dear Sirs, Is Lillet granite slightly porous? Is this stone known under different names like "Alba Roso" or "Sunset Rising"? Have you ever heard of these types of granite? With best wishes, C. Francet, Nov 10. Reply

R2: Dear Francet: Mmmmmmm .... "Sunset rising" .... That's a good one, all right!! No, I don't know. Run the lemon jiuce test to find out yourself about the absorbency and suitability (as material fo a countertop) of that particular stone. Ciao and good luck, Maurizio, USA, Expert Panelist. Reply

R1: Dear C. Francet, Lillet granite is slightly porous. Alba Roso or better Rosso Alba is Iranian marble, Sunset is granite from USA, maybe granite from India, Sunrise is Indian granite. Daniel, Slovakia, Expert Panelist. Reply

 

A 1154: Please email me relevant information on marble, slate and fossil stone. I need information on the materials characteristics, types of bonding required and its maintenance. Any photographs you may be able to forward me will be greatly appreciated too. Many thanks, Yvonne, USA, Oct 25, Reply

R2: Dear Yvonne: There's a science that's called Petrography (it's a branch of geology), and there are a lot of publications and books availalbe in book stores, libraries and Amazon.com. Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

 

R1: Hi Yvonne, You want a lot information. Marble is a crystalline rock composed of crystalline grains of calcite, dolomite, or serpentine  (composed of hydrous magnesium silicate). It is capable of taking a polish. For more info refer to ASTM C119. Slate is a fine grained metamorphic rock derived from sedimentary shale. Also in ASTM C119 Fossil Stone. Could be Pre Cambrian material that would be classified as a marble but quite dense. Installation methods vary based upon substrates. I will generally say a thined method will install all these floors in an interior. With wood sub-floors you need to reinforce the deflection to a minimum of L 720 before applying the thin bed method. Maintenance will be washing the floors with good neutral cleaners and water frequently. Impregnating as required and with the marble maybe looking at a type of appropriate sealer. Good luck, Steven, USA, Expert Panelist, Reply

 

A 1152: I want relevant information on the properties of sandstones and their uses in construction please. 
Roberts, USA, Oct. 23. Reply 

R1: Sandstone has been used as a building material for as long as man has been building.  However, the term sandstone encompasses a wide range of material, and as with limestones, all are not suited for construction purposes.  Factors involved include grain size, and how well cemented together those grains of sand are. A poorly cemented loose grained stone will not hold up for very long, while some of the tightly packed, well cemented stones, particularly those with a siliceous cement, are hard to work even with diamond saw blades.  The down side to sandstone is its porosity.  They tend to absorb a lot of water, and freeze thaw cycles can do a lot of damage.  Here in Texas, we are doing a lot of restoration on 1880-1890 vintage court houses. Some are built of Texas Granite, and for the most part, that stone is still in good shape.  Most were built of one of the several Texas limestones, and many of these utilized a red sandstone for trim details and ornamentation.  Its this sandstone that has deteriorated and is needing replacement.  The limestones also have held up well.  As a carver, I can tell you this. Sandstones are often beautiful stones, but they are all hard on tools, hard on the lungs, and not a lot of fun to work with. JVC, USA, Expert Panelist. Reply

 

A 1142:Do all pieces of granite have pin-holes? If so, to what extent would it be acceptable when purchasing a slab of granite? Do some colors of granite have more pin-holes than other colors? Jane, USA, Oct 13. Reply

R4: Jane, The short answer is yes. Many times in granites the surface is not completely smooth, and some granites are more prone to this than others (those with soft minerals that will abrade out during the polishing process). What has happened in the past is when the slabs were reviewed a decision was made on whether or not to accept the material. The companies processing the slabs presumed that the pits would not adversely affect the overall aesthetic or performance of the stone (they were not thinking about sealing it or using it --just selling it!). We now see many of these slabs come with resin applied before the polishing phase. This practice decreases the pitting and gives a more consistent gloss. However, the long term affect of this practice has never been studied. Regards, Steven, USA, Expert Panelist,  Reply

 

R3: Yes, they do. Considering that the vast majority of stones traded as granite are not granite by a long shot, no rule could be set on how many "pinholes" represent a standard of acceptability. Please realize that, unfortunately, the stone industry worldwide is pretty much unregulated. It seems that consumer protection laws don't apply when it comes to natural stone. Everybody can sell you something under the label that they please and with the (unofficial) grading that they care to disclose. Despite my deep love for natural stone, sometimes I feel ashamed to belong to this industry. Sorry, I'm upset. Ciao and good luck, Maurizio, USA, Expert Panelist,  Reply

 

R2: Dear Jane, Pin-holes are also known as pits and they are most conspicuous when viewing a polished stone surface from an angle so that it is reflecting a light source. They occur in most granite varieties but also in rocks termed granite in the stone trade that compositionally are not true granites. These include the higher grade metamorphic rocks such as the swirly varieties, multicolours, gneisses and schists. Most of the pin-holes or pits to which you refer are the result of the polishing action used in the processing of these stones acting on a soft or abradable mineral. Mostly these soft minerals are platy or flaky and include the micas (such as biotite and muscovite), chlorite, clays, serpentine, talc, and to a lesser extent the more fibrous amphiboles anthophyllite and actinolite. When biotite and muscovite are fresh and coarsely crystalline there is usually little pitting during the polishing process. However, biotite can be easily altered by hydrothermal activity and degraded structurally or chemically, or partially to completely altered to secondary minerals the most common of which is chlorite. Because chlorite is quite soft its surface is susceptible to abrasion during polishing and a small pit results where some of it has been removed. Most of these types of pits tend to be scattered and are easily seen in the reflection described above. This is the general situation for most pits, i.e. where original rock-forming minerals have been altered to secondary minerals that are markedly softer. Other examples of pits are where feldspar cores have been altered to clays (can result in deep, conspicuous pits) or where ferromagnesian minerals such as orthopyroxene and olivine have been altered to clays, serpentine, talc and chlorite. In the high-grade metamorphic rocks (especially those swirly ones and multicolours) the grainsize is usually much finer and the abundance of the micas relative to the harder minerals is much higher. During the polishing process many small flakes can be removed and a surface will result with numerous closely spaced pin-holes. The resultant polished surface is quite "open", and reflectivity is diminished. More importantly, these pin-holes result in elevated fluid absorption and this is often a source of considerable disappointment and unhappiness for many customers. These types of absorptive stones must be religiously sealed and maintained and I would never recommend their use in kitchens where oil spillages could occur. To overcome the pin-hole appearance it has been discovered that certain short-lived substances are applied to the slab surfaces by some suppliers. Pin-holes also occur on a microscopic scale with the effect of a "frosted" or honed appearance. Processors will complain that some schistose rocks won't take a polish. This is simply a mineral orientation effect and incorrect direction of slabbing. Another example of a microscopic pitting can occur where a syenitic green granite from the northern hemisphere is heavily dusted throughout with tiny carbonate crystals. When installed in a city environment these tiny crystals are subject to alteration or to conversion to gypsum with a resultant loss of polish. If you don't like the pin-hole effect you will probably not enjoy the problems that you might encounter with the stone after installation. If you want quality, negligible maintenance, and a retention of original appearance, choose a granite that "closes" well. Many of the fine-grained black granites fall into that category but there are also some classy greys and some greens. They will cost you a bit more but you shouldn't regret it in the long-term. The moral of this story - choose wisely. (Dr.) Hans, Australia, Expert Panelist, Reply

 

R1: Dear Jane: The pin holes you are talking about are probably minerals plucked from the surface during polishing. The most likely mineral to form pin holes would be biotite (a black mica). The acceptance level is up to you, the level will depend on the end use of the stone. Lighter coloured granites are likely to have less pin holes, but it is also a function of the quality of the polish. It really depends on what you think is acceptable at the price you are paying. Regards, Jim, Australia, Expert Panelist, Reply

 

A 1126: Can you give me the weight of marble, granite, limestone per cubic foot? Thanks Maddux, USA, Oct 6, Reply

R4: Dear Maddux, weights for limestones are 112 - 168, for marbles 168 - 181, for light granites 161 - 169, and for dark granites 182 - 193 pounds per cubic foot. Daniel, Slovakia, Expert panelist. Reply

 

R3: There are many varieties of stone. The density of stones ranges from 130lbs (typically limestone) per cubic foot to 175lbs (typically marbles and granites) per cubic foot. Some weigh less some weigh more. Bob, USA, Reply

 

R2: Granite typically weighs 160-170 pounds per cubic foot, limestone can vary from 130 to 160, marble is about 145 -160. Regards, Jim, Australia, Expert Panelist, Reply

 

R1: As a general rule, limestones are the lightest stones, granites the heaviest. Most limestones range between 140lbs to 150 lbs per cubic foot, marbles up to 160 + lbs, and granites can be in the 180lb. range. Weight of the stone depends on two factors, the type of mineral content, and how closely these minerals are compacted. Limestones are composed mostly of calcium carbonate (calcite) which is a relatively light mineral, and marbles are limestones that have been altered by geologic processes involving extreme pressure and heat, so that the crystalline arrangement becomes much more dense (tighter). Granites on the other hand are composed predominately of silicate minerals, along with a whole variety of "heavy minerals", and since they form out of solution (magma) the structure is very close knit with very little intercrystalline void space. Any way, these are only generalities, and since each stone is unique in its chemistry and deposition, it would be best to ask your supplier what each of the stones you are considering weighs. That information should be available. JVC, USA, Expert Panelist, Reply

 

A 1124: I have a number  of clients asking about?? sp. 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. Reply 

R1: "Pyroclastic lava" has no sense. There are products of lava flows or pyroclastic flows. Lava flow products are e.g. basalt, andezite, rhyolite. Pyroclastic flow products are e.g. 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, Expert Panelist. Reply

 

 

MY GRIPE:  I am an end-user who contracted for the delivery of some Italian granite tiles, 60 mm x 60 mm x 3/4 worth some $ 80,000 in various colors, among them Blanco Pero or Blanco Pera. Delivery is almost complete. However, recently I have had reason to suspect that the granite tiles supplied to me did not come from Italy but from China. I have heard that this is happening particularly in Asia. Could you tell me if you know any quantitative and qualitative tests that I can use to determine if I have been duped? Would you also have an expert in the Asian region? Ayette, USA, Reply

R4: I think this is not BLANCO PERA but Spanish granite BLANCO PERLA. Daniel, Slovakia, Expert Panelist.

R3: The only quantitative method to use is to check the physical properties of the stone such as density, absorption, etc. There are a group of stones from the Carrara and Massa section of Italy. When you buy such quantity you may want to speak to the quarry to see if they remember the order. You probably want to use the Italian word for white-- Bianco, however. Ask what grade of marble you receiving is i.e. 1 - 4 and what group it is from. Expect the Italian variety to be Group A (very sound). Best of luck! Steven, USA, Reply

R2: It is very simple to find out if what you are supposed to have is what you really do have.  A petrographic analysis is straight forward and fairly cheap method of characterizing every rock.  It is a bit like DNA testing in that it is extremely unlikely that rocks from two different continents are identical in their mineralogy, texture, and structure.  However, it does have to be done by a specialist - preferably one in the stone game.  The "perpetrators" of any possible substitution might come back and say that the petrographic analysis is invalid because of natural variation in natural rock tiles.  This argument does not stand up scientifically.  If any
argument got more serious then there are many other somewhat scientifically more sophisticated methods for fingerprinting rock, e.g. isotopes.  So, all you have to do is get small pieces (20mmx10mmx10mm, or a little bigger) of the stones and have them analysed.  The hardest part is to get someone reputable who could supply you with a small piece of broken tile of the two genuine European stones so that they can be used as reference material. Hans, Australia, Expert Panelist. Reply

R1: A Spanish name for an Italian "granite" that's perhaps coming from China!... That gives a brand new meaning to the definition of international trade! I have no answer to your question. You may want to try with some University (Pennstate, maybe). All I can tell you is that Italy is, by far, the largest producer of dimensional stone in the entire world. The fact is, however, that the stones coming out from Italy are not necessarily quarried in Italy. Italian producers buy blocks from just about all over the world, they process them into slabs and / or tiles, then off they go! You may want to consider demanding the importer to disclose the exact location of the quarry for you. If they tell you the quarry is, in fact, in Italy, let me know where and I'll find out for you if they're telling the truth (I still have strong contacts over there!) Ciao and good luck! Maurizio, USA, Expert Panelist. Reply

My Gripe: Hi, I am from an architectural practice in Singapore. Currently, we are having some problems in the project we are doing. They are mainly condominium. The purchaser complained that the marbles are cracked which we told them they are actually the veins of the marbles. When you run the fingers on the veins, you can feel that there is a slight uneven edge. What method should we use to determine whether the marbles are actually having cracks in the surface? What should we look out for as architect during the selection of marble? Would be appreciated if you could answer my queries. Anyway, the marble we are using is Rosa Zarci from Spain. Thank you. Regards, Chong, Sept 24, Singapore, Reply 
R3: Dear Chong, There are many marbles and limestones that have naturally occurring cracks and some that appear like cracks but are filled with material of different composition (or degree of crystallinity) to the host stone.  Limestones tend to have a greater diversity of "cracks" than marbles because they have usually not been subject to the geological processes responsible for the formation of the more crystalline marbles.  During the changes that occur from limestone to marble (metamorphism) some of the naturally occurring cracks or crack-like features disappear.  Many limestones contain squiggly lines that are called stylolites.  These are simply pressure solution features inherent in limestone formation.  Some are open, some closed and some a bit of both.  Most of them do represent  planes of weakness. Other limestones contain squiggly or irregular lines that contain minerals such as hydrated iron oxide and clay.  These are usually brownish and related to the mode of formation of the limestone.  For example, when a large area of limestone reef collapses, thin beds of clay, hydrated iron oxides and other substances can mix in with the many fragments that now constitutes the
limestone.  Because these other substances are often darker in colour than the carbonate in the limestone they appear to stand out visually.  Depending on the types of finish of the limestone many of these other substances are also slightly harder than the carbonate and therefore have the feel of a ridge.  Sometimes the limestone undergoes diagenetic changes which lead to the formation of thin veinlets of clear to whitish, slightly more
crystalline carbonate.  These can look very similar to cracks but they are in fact healed.  The formation of marbles from limestone by metamorphic processes involves many influences of which temperature, pressure and tectonic forces are particularly important.  During these changes some new minerals are usually formed and there is usually considerable mobility of substances.  This can lead to many weird and wonderful textures in marbles including a wide range of veins and structures. Depending on the composition of these veins and their relationship to the host rock some of these vein types can be as strong as the rest of the marble but others can be a source of weakness.  Because marbles are intrinsically brittle (i.e. very small amounts of movement will cause fracturing) it is difficult to process some marbles.  To prevent the slabs from cracking and falling apart some marbles are strengthened with resin and backing material and occasionally there is the additional requirement of stainless steel rods. It is important to realize that there are many different types of "cracks"
in limestone and marble.  If there are cracks present in the variety that you have selected for use on or in a building it is essential that you find out why these cracks are there and whether there is the likelihood for more
to develop once the stone is in place.  You might need to find out the correct fitting or laying procedures for that particular stone and you need to look at its likely durability and performance.  There are some carbonate
stones that will pit, spall, and start to disintegrate in only a short time after laying.  If it is in a commercial situation you need to have a maintenance schedule in place.   For these reasons it is highly recommended
that architectural practices have access to a consultant geoscientist specializing in stone.  (Dr.) Hans, Australia, Expert Panelist, Reply

 

R2: Dear Chong: The marble you mention (actually a compact limestone) is, like many other Spanish (and Italian) marbles, a class C-D stone. Which means it has a lot of natural flaws, mainly holes and fissures. There's probably some (secret) grading within the quarry, but I doubt very highly that anybody will ever tell you. (Why should they: It's a lawless industry!). You're asking what you should be looking out for when selecting marble. Wrong question, my new friend from Singapore! The right question is: WHO you should be looking for when selecting marble. Answer: A true stone expert. Petrography, like all other sciences, can't be condensed in a telegram. For what's my experience, most architects and other specifiers have the tendency to choose stone only by their looks and color. An intelligent selection goes much deeper than that! Of course, I (and many others, I'm sure) would be available to assist you (and other specifiers, of course). For some mysterious reason that I can't quite grasp, however, I seem to find some solid resistance when I break the bad news that I charge for my consultation services! Ciao and good luck, Maurizio, USA, Expert Panelist, Reply

R1: You need to have a petrographic thin section made of an area of the marble that has linear feature through it.  The crack lining needs to be examined for the presence of coatings.  If the feature is actually a vein or stylolite it will show some evidence of filling, if it is a crack (possibly caused during extraction) then the crack face will be clean and no different to the rest of the material.  A piece of marble the size of a match box is required for this examination. I have broad experience with such problems and I can do this for you for $250USD, please contact me if I can help. Regards, Jim, Australia, Expert Panelist, Reply

A 1115: My request is very in general: I teach material technology and chemistry and write my 6th book; it is about Material technology in Ancient Egypt. So everyone who can and will contribute whatever to these activities in the area of stones is invited! I am at the beginning so everything is welcome. More questions? Please ask me! Bormans, Netherlands, Sept 28, Reply

A 1114: Would like to know what grades there are for marble and how they are rated. Sept 26, USA, Reply
R3: There are 4 classifications of marbles. Class A, being the most resistant to breakage and having the least amount of natural inclusions, veins, and inconstancies.
Class B, Class C, and finally Class D, which is the most likely to break because of the above reasons. Normally, the class A materials are more consistent looking while the Class D marbles are more ornate. Class marbles
would usually be harder and more dense, while Class D marbles would be softer and more porous. Hope this helps. Bob, USA, Reply

R2: Marble is classified in 4 grades.  Grade A is sound, uniform marble with no flaws or voids.  Grade B is similar to A but may have some occasional faults that may need filling.  Grade C has variable in quality with some
flaws such as veins, voids and lines of separation. These faults are usually filled and reinforcement may be necessary.  Grade D is similar to C but with a higher proportion of faults and requires filling and/or reinforcing.
Regards, Jim, Australia, Expert Panelist, Reply

R1: There are four groupings that are basically arbitrary.
Group A-- Any marble or stone that can be had in regular rectangular blocks of commercial size. Usually sound and free from natural defects. Finishing is at a minimum cost.
Group B-- Same as group A except the size of the blocks maybe smaller. Finishing cost may be higher due to texture and size of slabs.
Group C-- Any marble or stone that cannot be sold as sound. This stone will have minimal natural defects such as fractures, surface voids, dry seams etc. This requires rods or reinforced liners.
Group D-- any marble, stone, serpentine, onyx or breccias. Irregular shapes and the most reinforcement available. Steven, USA, Expert Panelist, Reply

 

A 1113: I want to know which stone is the best and why between polished China, India or African Black. We are getting a stone for our daughter’s grave and these three are our choices. But we are told by some the China and some the African. We was wanting to ask someone that isn't trying to sell us which one? If you would be so kind to help us decide. Thank You, Debra, Sept 24, USA, Reply
R1: Just make sure the stone is not oiled to make it look blacker than it really is. See our Library of Articles.
The Indian stones are the best for monuments (See our Stone Album.) Do note that there are hundreds of quarries in India so there is a lot of variation. What is most popular (highest priced) are fine-grained deep black
granites. Finally, it is a question of what really appeals to you. Polish quality, workmanship, etc. are independent of the stone quality. Basically, you do not want material defects like flecks, etc. Generally, the bigger the grain size (crystals), the lower the price. Vinay, India, Reply

 

A 1109: I am a research student looking for relevant information on serpentine. Ty, USA, Sept 24, Reply
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, Expert Panelist. Reply

 

 

A 1115: My request is very in general: I teach material technology and chemistry and write my 6th book; it is about Material technology in Ancient Egypt. So everyone who can and will contribute whatever to these activities in the area of stones is invited! I am at the beginning so everything is welcome. More questions? Please ask me! Bormans, Netherlands, Sept 28, Reply

MY GRIPE: A 937: Hello. Love your site! Very professional and informative. I was wondering if you'd be so kind as to give some advice on how I should proceed in my dilemma  (I should say... my parents dilemma).... My parents recently purchased a new home and it is in the process of being built. They purchased a Granite kitchen counter top from a display sample. What they ordered was "Juparana Colombo"  (not sure what country of origin - it was purchased via the home builder.) Anyway, now that the Granite counter top is in place it looks nothing like the sample they were shown - even though the builder is claiming that is what stone they ordered.   There is a very noticeable "dark grain" down the middle of it and the stone itself looks a little darker.  My parents are mostly unhappy with the very noticeable grain down the middle  -  is this common for Juparana Colombo ????   90% of the pictures I've seen on the Internet indicate not so! Knowing nothing about Granite I thought I'd turn to you guys to see if you could shed a "little light" (no pun intended) on the matter.....   any suggestions on how to proceed with the builder???   Any advice is GREATLY appreciated !! Thanks so much.... And have a great day ! Ken, March 9, USA. Reply
R1: They did sell you an inferior quality. Many stones have such patches and slabs with such patches are usually sold at discounted prices. Regarding the shade itself being darker, they should have matched the sample. If they could not deliver a matching shade, they should have taken your parents' permission. The solution is to get a discount or a replacement. FindStone. Contact

 

MY GRIPE: A 1052: I have been in the stone industry for 6 months. I am an assistant manager: operations / salesman for a large stone center in the southeast. About 90% of our business is wholesale to the trade of about 140 different types of stone (this includes varying thicknesses of the same stone): fieldstone, flag, bulk material, bluestone step treads, cobblestone, etc. I can identify all the types of stone we sell, and give a few uses for each, but that is about all. We have only been in business 3 years and although we have a fantastic selection of stone we are a small staff. Most of the knowledge I have obtained has been through my own hard work. I have been given VERY little training. I know I sound knowledgeable to homeowners, but some of the contractors who have heard me explain things to the homeowners don't really want me to help them, because they know I am bullshitting them. I don't want to BS anyone. I truly want to become very knowledgeable and an expert in this wonderful field. I want to learn everything I can get my hands on about the application of the stone we sell, as well as other types of stone we don't sell that is available throughout the US, Canada and Mexico. I want to purchase books on stone in architecture. I am interested in learning how to apply stone with various projects, so I may use this information to sound more knowledgeable to contractors and homeowners. I also want to learn how to estimate jobs for contractors regardless of what type of stone they plan to use. Your help with these matters is greatly appreciated. I have had a difficult time searching the web for information. Thank you for your help. Sincerely, Dan, USA, July 22. Reply

 

R1: Dear Dan, you can read the articles in FindStone - Library of Articles.
I can recommend you some books written not very scientific:
F. Bradley (Studio Marmo): Natural stone.

A Guide to Selection. W.W. Norton & Company, New York 1998.
E.M. Winkler: Stone in Architecture. Properties, Durability. Springer-Verlag, New Your 1994.
J. Ashurst & F.G. Dimes: Stone in Building. Its Use and Potential today.
The Architectural Press Ltd, London 1977.
Daniel, Slovakia, Expert Panelist. Contact 

 

A 1089: This is a difficult enquiry.  Sorry to be asking you this one.  I have been working on beige granite for several years and recording numerous observations on the behaviour of this granite.  The rock type is a leucoadamellite with SiO2 close to 75%.  Most of the sparse annite-rich biotite has been replaced after emplacement by pennine (chlorite). There are no other ferromagnesian minerals.  Rare, narrow zones occur within the granite that are enriched in quartz and are noticeably more chloritic. Most of these zones carry a little finely disseminated pyrite which is mildly reactive and tends to oxidize.  Pyrite crystals occurring in druses and
miarolitic cavities is chemically stable and will not oxidize. There are also late-stage systematic quartz veins carrying a little molybdenite. Little specks within these veins also oxidize but they do so rapidly and tend to be bluish-grey. The stains disappear after several weeks so these are not of concern.  The reason for the long-term research is that the granite will discolour under certain conditions which I will outline shortly.  The discoloration is a selective yellowing affecting all the minerals evenly (mainly quartz, alkali feldspar, and sodic plagioclase feldspar). The extremely thin film can be easily removed with a moderately strong solution of sulphuric acid that is applied and then thoroughly washed off after 5 minutes.  Once removed the incidence of the stain returning is low.  Similarly, once a section of the stained surface is chipped off in situ it will not re-discolour.  A large sliver of granite separated from the mass by a fracture will never stain. The conditions of the stain's appearance include an environment of high alkalinity such as in proximity to expandite (expanding cementitious product used to fracture the granite), nitrogen-rich explosive, and alkaline mortar. With the expandite the stain forms in a narrow zone (3-5cm) about 10cm on either side of the drill hole containing the product. Additionally, an infinitely elongate stain will form under the drill holes containing this alkaline product.  With the explosive the stain covers the entire area where the explosive has had substantial contact (about 25cm).  The use of the explosive is restricted to a pushing effect after the granite blocks have been split.  Where a large block of granite rests on another on a small point there will be a rainbow-shaped stain about 5cm wide and about 20cm from the point of contact.  Where the granite blocks are left to rest on the ground capillary action will draw the stain upward but it will never reach or stain a horizontal surface.  Free metallic iron also will rapidly affect the granite surface to produce a very localized stain - such as from wedges, drill steels, excavator scrapes, and in the processing yard, a more general stain from metal shot from gangsaws and from circular diamond blades. If slabs are cut and stacked without washing the stone will stain along the bottom of the slabs.  I understand from communication with other scientists and processors that similar beige granites of the world also possess this characteristic.  Do you have any ideas or contacts that might shed some light on this problem??  There are still some things that I need to try but this explanation will do for now. I am trying to track down a US geoscientist who specializes in the mobility of iron during granite weathering and hope that he can provide some clues. However, he is elusive and probably out of the university system. There is no doubt that the original cause of the staining is fluid-driven and that porosity (0.24%) plays a significant part in the capillary action. In many respects there is a strong similarity between the staining of this granite and Liesegang ring formation. Fluid also plays a major role in the staining during the fixing of the granite.  Where it is laid wet on a sloppy alkaline mortar bed there is a high probability of a mild stain appearing within days of fixing irrespective of thickness (20-50mm).  If small 20mm thick panels are fixed on walls (as edging) with say 3 dobs of mortar a yellow stain will faithfully mimic the size of the mortar dob within a week.  If the adjacent panel is fixed with silicon there is no reaction at all.  It is mainly this selective reactivity, which is puzzling.  I would very much appreciate a response or continue the dialogue. Hans, Australia, Sept 4, Reply
R2: I have some ideas but I am not expert in geochemistry or chemistry. I suppose your beige granite contains rests of diseminated microscopic pyrite, because beige color is caused by scattered limonite which was
created mainly from the weathering of iron bearing minerals. I suppose pyrite or other sulphides which is common in metasomatic changed granites, because molybdenite presents. I think beige color is more
expressive in mineral cleavage of feldspar, maybe around chlorite?  Pyrite or other disseminated sulphides react with hydroxides (calcium, small amount of natrium and potasium)of mortar, explosives and expandites, and create acid salts which increase solubility of iron (ferric) hydroxide and it migrates and forms something like Liesegang rings (product of diffusion). Maybe the granites have suitable porosity (amount and size of pores) for this process. Explosives contain nitrates which release oxygen to pyrite oxidation... I cite the part of the page
http://www2.cr.nps.gov/tps/briefs/brief38.htm:  
The use of alkaline compounds should always be followed by a weak acid wash and a water rinse in order to neutralize-or remove-all the alkaline residues from the masonry. Strong alkalies (pH13-14), such as sodium hydroxide-based paint removers (caustic soda or lye), generally should not be used as they can cause efflorescence and staining on masonry surfaces, if not properly neutralized. Potassium and other hydroxide paint removers may react with iron compounds in some masonry, particularly Indiana limestone, to form dark brown
(rust-colored), or black ferric hydroxide stains, which are very difficult to remove.
Maybe the facts are known for you. We can discuss of the problem later. Daniel, Slovakia, Expert Panelist. Reply

 

R1: Hans, Have you given any consideration to the possibility that the behavior of this material reactivity is consistent with properties of certain limestones and serpentines. It seems that for panel installations the easy solution is to specify an epoxy setting bed. Your longitudinal discourse evidences the fact you are most knowledgeable about the physical properties. With a 24% absorption rate it would still be prudent to test a section. Another possible solution is to present your information to setting material company and let them tell you which products would be best to use. Also, if the ferrous material infiltrates all aspects of the stone and oxidizes with great consistency then I would not recommend utilization of the material. A sulphuric acid wash is not something any one here would be excited to do. Steven, USA, Expert Panelist, Reply

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, Reply
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, Expert Panelist. Reply

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

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, Reply

R3: Unfortunately for you, bluestone is 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, Expert panelist, Reply

R2: Bluestone is a sedimentary/ metamorphic stone. In the United States, 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. Reply

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, Expert Panelist. Reply

 

Id 1003 USA: Can you tell me if Pietra del Cardosa is granite?  How will it hold for a kitchen counter top?  Will need special maintenance? Aug 23. Contact

R1: Pietra del Cardoso is Italian grey sandstone, not suitable for countertop because it is not polishable and contents calcite. Daniel, Slovakia, Expert Panelist. Contact