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ADVICE WANTED!   July 31, 2002
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Marble Characteristics - General

Physical, chemical, technical characteristics of marble in general


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



Q 2236: I have looked at many articles in this very useful page, and have not come across a way to tell Marble and Granite apart just by looking at it. To the untrained eye they look very similar, I have also noticed that out of the two sample tiles I picked; one has a mesh type backing glued to the back. Any relation to the type stone it is if a mesh is seen? Hector, July 15,
R2: Dear Hector, granites are generally composed from visible multicolored grains. Typically grain of one color is connected with grains of other colors, e.g. grey quartz is close to pink orthoclase, white plagioclase, black mica. Granite is a mixture of minerals. Marbles are either without visible grains of calcite (limestones), or connected calcite grains of similar color (true marbles). Daniel, Slovakia
R1: Dear Hector: Nobody can teach how to recognize marble from "granite". Usually, the mesh-type backing is typically applied to marble or travertine (they are more fragile than "granite")., Maurizio, USA
A 1591: Should I get "honed" or "satin" finish on my marble countertops? Dave,  March 25.
R1: Dear Dave: Honed or satin are different degrees of the same stuff. Get the one you like more. Maurizio, USA 
A 1532: Is there one place where I can determine the classification used by Spanish quarries for marble? For example, some use "Standard", others use "1a (primera)"... How does "classico" relate to these and "2a (segunda)" ? Gines, March 13,
R2: Crema Marfil has as many different classifications as companies you can find. The most common is:
Select/First Q.: Homogeneous, light colour, few veins
Standard: Homogeneous, normal veins
Classico: No homogeneous (spots, shadows..), more veined. 
The second is:
Select: Homogeneous, light colour, few veins
First Q.: Homogeneous, light colour, a few more veined
Standard: Normal, with veins
Classico (or commercial): More veined, with spots, resined. Overall it will depend on he type of classification of each plant. Jorge,
Spain
R1: Gines, it is very difficult to know that because it depends on each company. 
Generally speaking is like that: 
Primera=First quality (It' s selected very well) 
Segunda=Commercial=Second quality (Its the less uniform in respect to the color) 
Standard=Its the most quarried. (Its uniform but not the best quality) 
Regards, Francisca, Spain,
Thank you Francisca and Jorge for your . If you'll permit follow-up questions: When a Spanish marble company does not list the quality with the name of the marble, is it assumed to be "Standard" ? Also, how does "Extra Quality" and "High Commercial" fit into the list of classifications you gave me. Again, many thanks for your . Gines
A 1443: My husband just brought home a piece of stone, we think it's marble. It came from the basement of an old bakery. It is about 6 foot long, 2 foot wide, and 4" thick. He said it was very heavy, weighed 100s of pounds and took 4 men to move. The surface is pretty rough, looks well-used. How can we tell if it's marble and what can we do to make it smooth and pretty? Jennie. Feb 14.  
R1: Dear Jennie, That size sounds awfully suspicious! Did your husband check to see what was underneath this marble slab? To tell if it is marble requires a couple of simple tests. First of all go to the kitchen, get a pointed knife (not your best German quality), and find an inconspicuous spot that you are going to try to scratch. If it scratches fairly easily and comes up with a white powder from the scratch then it is likely to be marble. To be sure make a little extra powder and put a drop of vinegar on it. If is bubbles gently then you have confirmed that it is calcareous. What use do you have in mind? Because a piece that size is worth quite a bit of money (incidentally, if your sizes are right is should be close to 330kg) you might want to approach your local undertaker to see if he will buy it. Or you can use it as a garden bench. A sculptor might also be interested. (Dr. Hans), Australia,

A 1114: Would like to know what grades there are for marble and how they are rated. Sept 26, USA,
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.


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

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

A 1109: I am a research student looking for relevant information on serpentine. Ty, USA, Sept 24,
R1: Serpentine is usually dark green, veined, often brecciated, metamorphic rock which was formed from upper mantle peridotite rocks during collision of lithospheric plates. It is created from serpentinite and small amount of calcite, magnetite, chromite and pyroxene. The hardness of serpentinite is similar to marbles, but it is chemically more stable. Daniel, Slovakia

A 1557: I saw the marble Rojo Alicante and loved it. Now my builder tells me its grade D and "no good". Please advise me with all that you know. Its for my bathroom vanity tops. What should I do??? Thanks, Gina, March 20, Reply
R2: Use it if you like it. In a bathroom with proper fabrication and installation, it will be fine. When you get it, learn how to care for it. Regards, Steven, USA 
R1: Dear Gina, Rojo Alicante is beautiful to look at and stunning as a wall tile.  It's weaknesses are high traffic areas and exposure to wet/dry cycles.  The stone has stylolites (filled or partially filled veins) that are often filled with sensitive clay type minerals that may soften or deteriorate and leave gaps in the veins that need to be filled.  Being a calcite based stone, it is relatively soft compared to granite so scratches and loss of polish are a greater  issue as well as susceptibility to stains from acidic solutions.  but still, it is lovely to look at!Regards Jim, AustraliaReply

Q 909: I was told that Rojo Alicante was in Group D What does it mean? Does anyone have a reference where I can find the significance of Group A, B, C, or D? Susan, USA, March 17.

R1: Yes, the Spanish Rojo Alicante is a class "D" marble. Marble is classified in groups define by the first 4 letters of the alphabet. Class "A" marble is a marble that is very consistent all throughout its composition, with no natural fissures ("hairline" cracks) or cavities. Class "B" marble is not so consistent and it begins to show minor natural flaws (fissures, tiny cavities). Class "C", "C-D" and "D" are getting worse, of course. Should an "A" marble cost more than a "B", or "C", or "D" marble? Nope! Since Mother Nature charges nothing for all marbles, all marbles start out for free. It's mankind that invented the concept of "price". Price for marble -- like most any other commodities -- is determined by the forces of the market. "Demand and supply" is king! An attractive and scarce "D" marble will cost more than a plentiful but butt-ugly "A" class marble! Lets make no mistake, however. The classification above has nothing to do with what could be defined as a grading of the stone. There is seldom a case where from the same quarry you can get an "A" marble and a lower class one. Is an "A" marble "better" than a "D" marble? If one has to install, say, a marble floor with the "grind-in-place" method, then the A and D do make a difference. In fact, an expert operator will charge more to do a "D" class marble, because, at a certain point of the job, he will have to fill and "stick" all the open fissures and cavities exposed by the first couple of grinding cuts, whereas that extra-work would not be necessary in the case of a class "A" marble. But when all is said and done, at the end of the job, both marbles will be just as "good". It could even turn out that, from a daily  maintenance point of view, many a "D" class marble are even better than "A" class marble, and less susceptible to certain types of damages that could be caused by an accident. As far as grading goes, instead, that is better to worst quality within the same stone coming from the same quarry, a few quarriers volunteer some sort of grading. For instance, the Spanish Crema Marfil is graded - by the quarry - as "Residential" and "Commercial" (residential being the better grade). The Greek White Thassos comes in - again by quarry own grading - "Select, "AAA", etc. The Italian White Carrara is graded - again by the quarry following the A, B, C and D classification. So it's one of the few marbles that can be either "A", or "B" or "C" (to the best of my knowledge, there nothing under the "C" with this type of marble). The fact in the matter is, however, that all this (limited) voluntary grading from a few quarries here and there has very little bearing in real life terms. They are neither official, nor mandatory, and, as such, they have no "teeth" in a court of law. The stone industry world-wide is unregulated and the consumer is pretty much at the mercy of the dealer, assuming that the dealer itself knows anything about the stone it sells, which is not the case in all too many instances. And everybody's happy! Ciao everybody, Maurizio, USA,

A 939: One of my friend is doing research in chemistry. He would like to know how many varieties (colors) of marbles are available in India and what are the minerals which gives the color to the marble. Kindly . Siva, March 11, India,

R1: Dear Siva, I saw green, black, brown, white, grey, pink marbles. White color is caused by pure mineral calcite, green (black-green) color by serpentine (or some amphibole), black and grey by graphite (or organic
material), yellow to brown color by limonite, red to pink by hematite. Daniel, Slovakia,