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No change in size, 1 year ago
Physical origins: changed "high magnesium" to "magnesium-rich"
Marble is a rock resulting from [[metamorphism]] of [[sedimentary rock|sedimentary]] [[carbonate rock]]s, most commonly [[limestone]] or [[dolostone|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 [[crystal]]s. 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 minerals|silicate]]-poor) limestone or dolomite protolith. The characteristic swirls and [[Vein (geology)|vein]]s of many colored marble varieties are usually due to various mineral impurities such as [[clay]], [[silt]], [[sand]], [[iron oxide]]s, or [[chert]] which were originally present as grains or layers in the limestone. Green coloration is often due to [[Serpentine group|serpentine]] resulting from originally high magnesium-rich limestone or dolostone with silica impurities. These various impurities have been mobilized and recrystallized by the intense pressure and heat of the metamorphism.