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ADVICE WANTED!   July 31, 2002
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Materials Characteristics - General

Physical, chemical, technical characteristics of materials in general

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

Q 2302: Does the country of origin affect the quality and price of granite? Sussane, July 26, Reply
R1: Dear Sussane: The country of origin may effect the quality of the stone. Not the inherent quality of it, mind you, but the quality of the finished product. In other words, the same material processed into slabs or tiles, say, in Italy, would have better chances to be "perfect" than if it were processed -- even with the same machines -- in the country of origin. About the price issue, it doesn't matter where the stone was quarried and / or processed; only demand and supply determines that. Maurizio, USA 
Q 2298: Hi, I just put a big deposit down on new Barracuda granite tops and have a concern. They are coated with what looks like a resin. The vendor told us that it is put on at some manufacture's sites for extra protection. Is that true? I am worried it may be hiding something... They haven't gone to fabrication yet so can still pull out of the deal. Thanks, Mark, July 25.  
R1: Dear Mark; I'm a little confused, here. You can actually detect the coating of resin??! 
If that's the case, get the heck out of there and run as fast as you can! 
"Resining" "granite" slabs is a relatively new practice that's implemented mostly in Italy. It seems to make the "granites" more presentable (no obvious natural pits or fissures anymore) and, at the same time, liquid-proof (there's seldom need of applying an impregnator-type sealer to a properly "resined" stone. It does work, although the long term effects are still 
unknown, but the resin is not supposed to be seen; it's supposed to be inside the stone. Maurizio, USA 
Hi Maurizio, Thank you for responding to my question. I reviewed the RTB section and it was informative but I didn't actually address the new stone coating process. 
Actually, the stones "coating" is really only apparent on the edges. That's where I noticed it in the showroom. It is manufactured in Italy so the process you are referencing may be a reality. This is going to be a real heart -break for us as we love the stone. Should I ask for a similar stone without the "coating?" I will contact the vendor in San Jose, CA and ask what EXACTLY is put on it. Cabinets are going in today and tomorrow so will get right on it...
Thanks again, Mark.
Q 2235: I am looking for the technical and physical properties of Phalstain Jeruslem Lime Stone. Is it good for usage at external facade cladding in the Gulf region? What is the minimum thickness required for 1700x400 mm panel for that? Thanks, Arch, Tamer. July 15. Reply
R1: Dear Arch: I have recently investigated in detail over 60 cream-coloured limestones
from all over the world for an architect who wants to do the same as you. We have 4 semi-finalists and Jerusalem limestone is not one of them! There are about 7 limestone varieties under the umbrella of Jerusalem limestone - which one specifically are you interested in? Unfortunately, your question is not sufficiently specific to allow me to answer you. For example, which Gulf, is it covered by a roof, what are the fixings, to what height, etc. Dr. Hans, Australia
Q 2229: I would like to get a book about stones. Dingpastrana, July 15, Contact
R1: Dear Dingpastrana: If you can't find the information about stone that you're looking for in this very site, log on Amazon.com!!! Ciao and good luck, Maurizio, USA
Q 2228: My husband and I are interested in buying a stone home that was built in the early 40's in east Tennessee. The lines and the warmth of the stone exterior are what attract us to this home. My concern is with the color of the stone. It has a pink cast and I would prefer gray or brown. Is there a product that can stain or glaze a stone exterior that and might knock off the shade of pink?, July 15, Contact
R1: Dear Christy: Staining stone??? Please!!!!! You'll have to learn how to appreciate what you have and live with it! Ciao and good luck, Maurizio, USA
A 1941: I am looking for information of natural stone. Particularly the hardness and porosity of marble, limestone, and slate. May 21, Reply
R1: Take a look at our library section. FindStone.com
You have an awesome library. Thank you for all the information, it was very useful. 
A 1940: I am building an addition on my house in PA and the exterior is a very rusty fieldstone (sandstone), which has rusted to the point of almost looking like it was dipped in a vat of rusty water, then dried. The stone is no longer available from the original source, but I have found a similar stone with similar iron deposits in it. I would like to know what I could apply to it in order to accelerate the rusting process so when it goes up it will match the existing house. Thanks. Rich, May 21.
R2: Trying to put 60 years of natural weathering on overnight, eh? Well, as you mentioned, the rusty appearance is the result of iron deposits in the stone oxidizing, so to hasten the process, one would need to apply an oxidizing agent. Hydrogen peroxide comes to mind, but I have no idea if it will be effective. Wouldn't hurt to test an area with it. Good luck, JVC, USA
R1: Dear Rich: I honestly don't have the answer, but if I were you I would try to soak a sample of the new stone in a bath of vinegar. It may just work. I do know that if you rub white vinegar on a bare sheet of steel, it rusts right away. It's just a hunch. Keep me posted. Maurizio, USA
A 1918: I was under the impression that in order for a rock to be classified as granite, it must be light in color due to the overwhelming presence of feldspar and quartz. Please advise, Norman, May 16, Reply
R1: Dear Norman: Your impression of granite classifications is close. Granitic rocks are
classified according to the contents of three minerals - quartz, alkali feldspar and plagioclase feldspar. Mostly these minerals are light in colour. Quartz is usually clear, greyish or light brownish. Alkali feldspar is usually reddish, pinkish, greyish or white and the calcic variety of feldspar (plagioclase) can vary from white through grey to green, depending on the geological history of the rock. Together the colour is mostly light. However, certain geological conditions can grossly modify the colour of the feldspars and the quartz - yet the rock is still granitic in its composition. I have examined some dark brown rocks that were mineralogically granitic. Another good example are the green charnockites which can be dark green yet have a mineralogy which is essentially granitic (in the sense of the stone trade). Gabbros have a basaltic mineralogy (mainly calcic pyroxene, plagioclase feldspar, and opaque oxides) but the presence of small amounts of other minerals such as orthopyroxene, hornblende, olivine permits the use of modifiers or allows the use of another name. (Dr. Hans), Australia
A 1707: Site "Findstone.com" is very interesting, I am interested in knowing everything about "natural stones" of the world, its deposits, kinds, properties (physical, mechanical, chemical, technological), its utility for building and road-constructions and another...... 
I need this information for students didactic programs on geology deposits raw materials in Technical University of Mining and Metallurgy (AGH) in Cracow. Thank you, Karwacki, April 14.
R1: Dear Dr. Karwacki, I am your colleague from Comenius University, Bratislava. I am interested in natural stone since some years. I can recommend: 
- 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.
- L. Appel et al.: Naturstein - Lexikon. Verlag Georg D.W. Callwey, München, 1993.
- F. Müller: Internationale Naturstein Kartei - Kompakt. Ebner Verlag, Ulm.
and also my didactic article in Slovak about Bratislava stones:
www.fns.uniba.sk/prifuk/casopisy/geol/199954/pivko.htm and also try to address your colleague Dr. Janusz Magiera. Daniel, Slovakia  
A 1670: Is there a good source for the mechanical properties of building stone from the Arabian Peninsula, etc. Colin, April 8. Reply
R1: Dear Colin, there is an excellent source for this information.  Simply send some samples
of the stones that you would like tested accurately and cheaply to me along with the appropriate dollars and Bob's your uncle.  Sometimes a good petrographic analysis is all you need - much cheaper. 
A 1642: Can you direct me to a source for info on the hardness comparisons of granite, basalt and marble and spectrographs of the crystals? Any assistance will be most appreciated. Thanks, Garry, April 3. Reply 
R1: Granite is 7 on the moh's scale -- basalt about 6 -- and marble 5. See the Basic Information link on the left or www.findstone.com/articles.htm or go to a geological site and there are reams of information regarding material. Peace Prosperity, Tile Guy, USA. 
A 1633: I am from Bhutan, the land of the thunder dragon, which lies on the foothills of the Himalayas with India in the south and Tibet in the north. My father has a slate mine and I would like to know how to market it outside the country and we are also looking for markets in the USA. But I want to know if there is a TESTING CENTRE for ASTM in India or anywhere closer to my country. April 2. Reply
A 1483: I am attempting to find the definition of the term abrasive index as used in mining and quarry operations. Can you point me in the right direction? Is there a close correlation between this index and silica content? Regards, Rudy, USA, Feb 28.
R1: Dear Rudi, The abrasive resistance is expressed as an abrasive index calculated as follows. Abrasive Index = R1/R2 x 100, where: R1 = abrasion of the test specimen and: R2 = abrasion of the reference compound. Yes, there is a close correlation between this index and silica content, because silica is the hardest common mineral of the rocks. Daniel, Slovakia
A 1450: I am a marble polisher from The Netherlands looking for books or links to directories where I could find full specifications of marble compositions and natural stone types. Shay, Feb 18.
A 1431: Dears Gentlemen: Would you be so kind to send me the petrographic and petrologic analysis of Chocolate Brazilian Marble? Many thanks, Gomes. Feb 12. Reply
R1: Dear Gomes, If you would be so kind as to send me a sample of Chocolate Brazilian Granite plus $200 you will get the best petrographic analysis available. Add another $150 and you will get a petrological analysis. And don't forget to add a little extra (5%) for Findstone.com Dr. Hans, Australia, Reply 
A 1435: Is there a good product to stain new granite to look old. That is a new granite wall is being constructed adjacent to a granite wall constructed in the late 1800's. The old wall has a heavy 'patina' of lichen, mildew etc. Are there any products which promote growth of the above, or stains which could darken a new stone. Mike. Feb 12.
R3: Where I live natural yogurt is a favourite but needs to be kept damp for a while. Bryan,  UK,
R2: Mike.. this is always a problem when putting new work against existing work, and the existing work does not have to be very old for the weathering patina to start. Texas A&M experimented with a manure tea to hasten the patina on a brick addition with fairly good results. Basically the theory is to provide a nutrient source for the molds and lichens etc to feed on so that they will establish themselves more rapidly. Butter milk, and liquid fertilizer solutions have also been used. We have even gone to the extreme of burying stone in a compost pile for several months. But no matter what you try, remember that while you may be able to speed up the process, but there are no overnight solutions. Good luck, JVC, USA,
R1: One word gross. Why don't you clean the surface of the old to match the new? Regards, Steven, USA,
Thanks for the response.  Besides the fertilizing option are you aware of any stains that work on stone, similar to those used on concrete and CMU's? Mike,
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 was recently 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 think mud or concrete is ok with the heat. What can you tell me about this? Mary Jo. Nov 26.
R2: Dear Mary Jo: The solid surface supplier is dead wrong. Maurizio, USA
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. Steven, USA


A 1200: Our company is building an estate model home and is opening a residential development division for building high end custom homes and wants to obtain a book which details natural stone advising interior and exterior usage. We specifically need to understand specifications regarding staining tendencies, freeze thaw considerations and unique characteristics for all natural stone for interior and exterior flooring usage including terrace and pool decking. Can you recommend a good stone usage directory for this purpose? Please help. Thank you, Karen,
R2: Generally speaking there are many aspects to material suitability. Its make up, how its surface is prepared, what application it will be used for etc. Try and find what you like first and then ask about suitability to a
specific criterion. Best regards, Steven, USA
R1: Dear Karen, With 2700 granites on the world market and nearly 10,000 different stones of all varieties it is not possible to have a general stone usage directory that will tell you exactly what you want to know. This is particularly so because of the numerous finishes, thickness, structures, mineralogies, textures, and infinite situations into which these stones can be put. In your case, I would advise that you engage an expert stone consultant, present him/her with your plans and situations, and obtain the appropriate advice. When work is in progress or just before completion, engage that expert stone consultant again to provide you with a maintenance manual that covers all the stones, in all the situations for your high-end buildings. (Dr.) Hans, Australia
A 1183: Where would I find details on sandstone standard specifications for import into Europe (e.g. Germany)? By this I mean specs. in relation to hardness, tensile strength, compressive strength, porosity, permeability, sodium sulphate crystallization tests, etc. If you could give me a source, I would be grateful, Many thanks, Stuart, Nov 12. Reply
R1: The standards you are looking for can be found among DIN standards (Deutsche Norm) and CEN (European Committee for Standardization). Both of these should be accessible through the web. Some of the standards
will only be available as drafts at this stage. Regards Jim, Australia Reply

A 1154: Please email me relevant information on marble, slate and fossil stone. I need information on the material 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,

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, Maurizio, USA,


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 that a thinned 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. Steven, USA,


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

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

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

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

R1: As a general rule, limestones are the lightest stones, granites the heaviest. Most limestones range between 140 lbs to 150 lbs per cubic foot, marbles up to 160 + lbs, and granites can be in the 180 lb. 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. Anyway, 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,

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 an architect during the selection of marble? the marble we are using is Rosa zarci from Spain. Thank you. Regards, Chong, Sept 24, Singapore,  
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,


R2: Dear Chong: The marble you mention (actually a compact limestone) is, like many other Spanish (and Italian) marbles, a class C-D stone. This 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 stong solid resistance when I break the bad news that I charge for my consultation services! Ciao and good luck, Maurizio, USA

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, Regards, Jim, Australia

A 1115: I teach material technology and chemistry and write my 6th book; It is about Material technology in Ancient Egypt. So everyone who can 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,

A 1100: hope you can offer me some good advice! My wife and I recently purchased a sandstone fireplace (mantel and hearth) from a store in Scotland.  The showroom piece was perfect and yet when ours was delivered, there is an almighty mark across the sandstone hearth (approx. 70 or 80cm).  The salesperson says it’s a vein in the stone which he can do nothing about.  Is this true?  Is it normal to have such long running veins? We are really disappointed that such a beautiful stone has been made to look so unattractive by the marking.  Can you help me with advice on this matter so I don't have to rely on the salespersons 'partial' advice?  Thanks so much, Stephen, Scotland, Sept 14,
R4: Stone is a natural product and no two pieces of stone are identical - every piece is unique, and yours happens to have a quartz vein running through it.  That's probably the salesman's argument.  If you bought the
fireplace from a sample in a showroom, and you consider yours to be different, you may have some recourse for replacement through your local "consumer affairs' or "department of fair trading".  I would start by researching your local laws on these matters.  It is also worth noting that the quartz vein probably will not affect the functional nature of the fireplace - it is really only an aesthetic effect.  This could possibly be considered similar to buying a new car with a scratch on the paint work.  Good Luck! Jim, Australia
Dear Jim, Thanks for your input.  It’s really helpful and appreciated. Best regards, Stephen, Sept 18.

Unfortunately, yes it is true.  Sandstone, and limestone are both sedimentary formations, which means that they were deposited under water, for the most part.  Any thing that was deposited along with the mineral material (i. e. plant and animal remains, mud, other mineral concentrations etc) becomes part of the stone during the lithification process. Then there is a process of secondary mineral deposition and migration that occurs after the deposit becomes rock.  This is all to say that one can expect to find almost anything in a stone of sedimentary origin. The real problem here is that retailers do not inform their customers about these possibilities, and show room samples are generally fabricated from the most pristine stone.  As a fabricator of architectural ornamentation, I have learned how important it is to provide a client enough sample material either physically, or by description, that they understand before the order is placed. that there will be various inclusions, veins, and color variations, Even personally selecting the block at the quarry does not guarantee that I will have perfect stone, since no one that I know has X-ray vision, and to tell from the surface of a block what will actually show up in the sawed slab is impossible. Always, we use a disclaimer stating that natural stone is a product of nature, and subject to variations in color, texture, and content, and complete uniformity cannot be assured. Many of my clients appreciate these "flaws" because these are the things that distinguish natural stone from cast products. If the flaw in your hearth stone is such that you can't live with it, your only recourse is to reorder, specifying stone that matches the rest of the mantle.  A good fabricator will be willing to do this for you at no or minimal cost to you, because after all, customer good will, and word of mouth advertising is the life blood of our business.  Good luck, JVC, USA
Dear JVC, Thanks for your help.  I am certainly better informed now! Best regards, Stephen, Sept 18.

Stephen: Well the short answer is yes. However, we believe all fabrication facilities that custom make stone items for people should have what we call a slab or material review. This prevents the surprise you are feeling. I can't specifically answer what the store policy is in regards to customer dis satisfaction. Will they look and see if they have another hearth? Why is the showroom piece without veins if all others will have veins? Was the piece in the showroom sorted? Why was your not?  Does the salesperson and company not value your satisfaction? Are you supposed to know about this before you come into the store? Or- Is it attractive and as time goes on-- will it be construed as interesting? Your vein creates a unique hearth unlike any other. Is this a positive fact? Please be aware of the fact that all stone varies considerably block to block and sometimes even slab to slab. I am sorry about this. Steve, USA
Dear Steve, Thanks for your help.  These are good points for me to raise in my quest for a resolution. Best regards, Stephen, Sept 18.

R1: Dear Stephen: Geologically, yes it is possible, and, of course, nobody can do anything about it. The yard probably told you also (probably in writing) that variation from the sample can be expected, being that stone is natural product, etc. All that said, it's only up to them to decide to make a customer happy or not. Sorry, but cheer up: It's only money! Ciao, Maurizio, USA

Maurizio, Thanks for your honest input!  It is only money – it’s keeping my wife happy I am more worried about! 
Appreciate your help though. Best regards, Stephen, Sept 18.

A 1018: Usage: Inform me about hardness and absorption of various natural stones. James, USA. June 24 reply
R1: Hardness of natural stones:
light granites s.l. (with quartz) 6.5 - 7 Mohs scale
dark granites s.l. about 6
shales 2 - 3
sandstones 2 - 7
limestones, marbles about 3
dolomites, dolomitic marbles 3 - 4
slates 3 - 5
quartzites 7
vulcanites 5 - 6.5

Water absorption of natural stones:
light granites s.l. 0.1 - 0.35 (0.7)
dark granites s.l. 0.06 - 0.1
sandstones 2.5 - 7 (1 - 11) travertines 2 - 3 (15)
soft (porous) limestones 0.3 - 5
firm limestones (USA marble) 0.1 - 0.2 (0.4)
marbles (true) 0.01 - 0.2 dolomitic marbles 0.15 - 0.25
slates (0.01 - 0.1) quartzites (0.1 - 0.4)
vulcanites 1 - 20.
Daniel, Slovakia, Contact

A 963: Can any one tell me what is the Young modulus of marble? Avi, USA, April 19. Reply
R1:  Elastic material deforms under stress but returns to its original size and shape when the stress is released. There is no permanent deformation. Some elastic strain, like in a rubber band, can be large, but in rocks it is usually small enough to be considered infinitesimal. In materials science and geology, we often know the strain and want to know what stress produced it. The two versions are equivalent; the only difference is which side the constant is written on. The constant E is called Young's Modulus. Because strain is dimensionless, Young's Modulus has the units of pressure or stress, i.e. pascals.
If strain = 1, stress = E. Thus, Young's Modulus can be considered the stress it would take (theoretically only!) to result in 100 percent stretching or compression. In reality, most rocks fracture or flow when deformation exceeds a few percent, that is, at stresses a few percent of Young's Modulus.
The seismic P- and S-wave velocities in rocks are proportional to the square root of E.
For most crystalline rocks, E ranges from 50-150 Gpa, averaging about 100. If we take 100 Gpa as an average, and consider one bar (100,000 pa) of stress, we have: 105 = 1011 Strain, or Strain = 10-6. Thus, rocks typically deform elastically by 10-6 per bar of stress. This is a useful quantity to remember. Elastic strain in rocks is tiny - even ten kilobars typically results in only one percent deformation - if the rock doesn't fail first. Burzin Contact

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.
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.
A 1001: We are looking for a material with high heat retention.  We wish to heat the material to about 200 F. have it hold the heat for an extended period. Marble or Granite appears to the best, however, their may be other materials that could do a better job. Would appreciate any suggestions or information . Lin, USA. June 1
R1: Lin, Try soapstone. Best of luck! Steven, USA

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

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.

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
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.



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