About Marble
Marble is a metamorphic rock resulting from the
metamorphism of limestone, composed mostly of calcite (a crystalline form of
calcium carbonate CaCO3). It is extensively used for sculpture and
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 the metamorphosis of marble the original limestone rock is recrystallized
into an interlocking mosaic of calcite and dolomite crystals. The temperatures
and pressures necessary to form marble usually destroy any fossils and
sedimentary textures present in the original rock. 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 oxide 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.