Common marble varieties are granular limestone or dolomite. Marble is a rock composed of calcium and magnesium carbonate, mostly white and pink. Poiana Ruscă Mountains, Caraș-Severin County Types and Features Ī piece of blue calcite marble from the Precambrian period in New York State, USA Examples of notable marble varieties and locations Marble Bacterial and fungal degradation was detected in four samples of marble from Milan Cathedral black Cladosporium attacked dried acrylic resin using melanin. ![]() The haloalkaliphilic methylotrophic bacterium Methylophaga murata was isolated from deteriorating marble in the Kremlin. In this case the calcium oxalate (CaC 2O 4) formed in the reaction is washed away with the slurry leaving a surface that has not been chemically changed. The resulting reaction is as follows.ĬaCO 3(s) + H 2C 2O 4(l) → CaC 2O 4(s) + CO 2(g) + H 2O(l) The other often used method of finishing marble is the use of polishing with oxalic acid (H 2C 2O 4), an organic acid. ![]() This is harder, more glossy and stain resistant compared to the original surface. The resulting calcium hexafluorosilicate (CaSiF 6) is bonded to the surface of the marble. The chemical reaction below shows a typical process using magnesium fluorosilicate (MgSiF 6) and hydrochloric acid (HCl) taking place.ĬaCO 3(s) + MgSiF 6(l) + 2HCl (l) → MgCl 2(s) + CaSiF 6(s) + CO 2(g) + H 2O(l) It involves polishing the surface with an acidic solution and a steel wool pad on a flooring machine. Vinegar and other acidic solutions should be avoided in the cleaning of marble products.Ĭrystallization refers to a method of imparting a glossy more durable finish on to a marble floor (CaCO 3). Outdoor marble statues, gravestones, or other marble structures are damaged by acid rain whether by carbonation, sulfation or the formation of "black-crust" (accumulation of calcium sulphate, nitrates and carbon particles). Chemistry Degradation by acids Īcids react with the calcium carbonate in marble, producing carbonic acid (which decomposes quickly to CO 2 and H 2O) and other soluble salts : CaCO 3(s) + 2H +(aq) → Ca 2+(aq) + CO 2(g) + H 2O (l) These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism. Green coloration is often due to serpentine resulting from originally magnesium-rich limestone or dolomite with silica impurities. The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities such as clay, silt, sand, iron oxides, or chert which were originally present as grains or layers in the limestone. Pure white marble is the result of metamorphism of a very pure ( silicate-poor) limestone or dolomite protolith. ![]() Primary sedimentary textures and structures of the original carbonate rock ( protolith) have typically been modified or destroyed. The resulting marble rock is typically composed of an interlocking mosaic of carbonate crystals. Metamorphism causes variable recrystallization of the original carbonate mineral grains. Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite (rock). Folded and weathered marble at General Carrera Lake, Chile
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