Physical, chemical, technical characteristics of marble in general

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

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,