Pure limestone is white, but marble can be any color based on the impurities that may have existed in the original limestone rock. Marble is an excellent building stone due to its uniform texture, softness (calcite is a 3.5 on Mohs hardness scale), and inherent beauty.
The softness of marble and its relative isotropy and homogeneity make marble very desirable for sculpture as a building material, and in many other applications. The word "marble" is colloquially used to refer to many other stones that are capable of taking a high polish.
In commercial terminology, a marble is any crystalline calcareous rock that will take a polish. Even serpentine (a hydrous magnesium silicate metamorphic rock) is sometimes considered a marble because it is often cut by veins of calcite or dolomite and will take a high polish.
Pure white marble is the result of metamorphism of very pure limestones. 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 high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.
In the construction, specifically the dimension stone trade, the term "marble" is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone.
Marble is a metamorphic rock resulting from regional or rarely contact metamorphism of sedimentary carbonate rocks, either limestone or dolostone, or metamorphism of older marble. This metamorphic process causes a complete recrystallization of the original rock into an interlocking mosaic of calcite, aragonite (a crystalline form of calcium carbonate, CaCO3)and/or dolomite crystals(CaMg(CO3)2).. The temperatures and pressures necessary to form marble usually destroy any fossils and sedimentary textures present in the original rock.
Pure limestone is white, but marble can be any color based on the impurities that may have existed in the original limestone rock. Marble is an excellent building stone due to its uniform texture, softness (calcite is a 3.5 on Mohs hardness scale), and inherent beauty.
The softness of marble and its relative isotropy and homogeneity make marble very desirable for sculpture as a building material, and in many other applications. The word "marble" is colloquially used to refer to many other stones that are capable of taking a high polish.
In commercial terminology, a marble is any crystalline calcareous rock that will take a polish. Even serpentine (a hydrous magnesium silicate metamorphic rock) is sometimes considered a marble because it is often cut by veins of calcite or dolomite and will take a high polish.
Pure white marble is the result of metamorphism of very pure limestones. 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 high magnesium limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.
In the construction, specifically the dimension stone trade, the term "marble" is used for any crystalline calcitic rock (and some non-calcitic rocks) useful as building stone.
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