Marble

Marble is a metamorphic rock consisting of carbonate minerals that recrystallize under the influence of heat, pressure and aqueous solutions, most commonly calcite (CaCO3) or dolomite (CaMg(CO3)2) and has a crystalline texture of varying thickness. Marble is typically not foliated (layered), although there are exceptions. In geology, the term marble refers to metamorphosed limestone, but its use in stonemasonry more broadly encompasses unmetamorphosed limestone. Marble is commonly used for sculpture and as a building material. The word "marble" derives from the Ancient Greek μάρμαρον (mármaron), from μάρμαρος (mármaros), "crystalline rock, shining stone", perhaps from the verb μαρμαίρω (marmaírō), "to flash, sparkle, gleam"; R. S. P. Beekes has suggested that a "Pre-Greek origin is probable". This stem is also the ancestor of the English word "marmoreal," meaning "marble-like." While the English term "marble" resembles the French marbre, most other European languages (with words like "marmoreal") more closely resemble the original Ancient Greek. Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or dolomite (rock). Metamorphism causes variable recrystallization of the original carbonate mineral grains. The resulting marble rock is typically composed of an interlocking mosaic of carbonate crystals. Primary sedimentary textures and structures of the original carbonate rock (protolith) have typically been modified or destroyed. Pure white marble is the result of metamorphism of a very pure (silicate-poor) limestone or dolomite protolith. 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. Green coloration is often due to serpentine resulting from originally magnesium-rich limestone or dolomite with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.