Marbles

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 marble, granular limestone or dolomite (i.e., rock composed of calcium-magnesium carbonate) that has been recrystallized under the influence of heat, pressure, and aqueous solutions. Commercially, it includes all decorative calcium-rich rocks that can be polished, as well as certain serpentines (verd antiques).Science

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marble

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marble, granular limestone or dolomite (i.e., rock composed of calcium-magnesium carbonate) that has been recrystallized under the influence of heat, pressure, and aqueous solutions. Commercially, it includes all decorative calcium-rich rocks that can be polished, as well as certain serpentines (verd antiques).


marble quarry

marble quarry

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Related Topics: Parian marble Pentelic marble calcite marble Carrara marble onyx marble

Petrographically marbles are massive rather than thin-layered and consist of a mosaic of calcite grains that rarely show any traces of crystalline form under the microscope. They are traversed by minute cracks that accord with the rhombohedral cleavage (planes of fracture that intersect to yield rhombic forms) of calcite. In the more severely deformed rocks, the grains show stripes and may be elongated in a particular direction or e

ven crushed.Encyclopedia Britannica

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Science

Earth Science, Geologic Time & Fossils

Earth Sciences

marble

rock

Written and fact-checked by 

Article History

marble, granular limestone or dolomite (i.e., rock composed of calcium-magnesium carbonate) that has been recrystallized under the influence of heat, pressure, and aqueous solutions. Commercially, it includes all decorative calcium-rich rocks that can be polished, as well as certain serpentines (verd antiques).


marble quarry

marble quarry

See all media

Related Topics: Parian marble Pentelic marble calcite marble Carrara marble onyx marble

Petrographically marbles are massive rather than thin-layered and consist of a mosaic of calcite grains that rarely show any traces of crystalline form under the microscope. They are traversed by minute cracks that accord with the rhombohedral cleavage (planes of fracture that intersect to yield rhombic forms) of calcite. In the more severely deformed rocks, the grains show stripes and may be elongated in a particular direction or even crushed.


The environmental impact of Carrara's marble quarries

The environmental impact of Carrara's marble quarriesOverview of marble quarrying in Carrara, Italy.

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Marbles often occur interbedded with such metamorphic rocks as mica schists, phyllites, gneisses, and granulites and are most common in the older layers of Earth’s crust that have been deeply buried in regions of extreme folding and igneous intrusion. The change from limestones rich in fossils into true marbles in such metamorphic regions is a common phenomenon; occasionally, as at Carrara, Italy, and at Bergen, Norway, recrystallization of the rock has not completely obliterated the organic structures.


Most of the white and gray marbles of Alabama, Georgia, and western New England, and that from Yule, Colorado, are recrystallized rocks, as are a number of Greek and Italian statuary marbles famous from antiquity, which are still quarried. These include the Parian marble, the Pentelic marble of Attica in which Phidias, Praxiteles, and other Greek sculptors executed their principal works, and the snow-white Carrara marble used by Michelangelo and Antonio Canova and favoured by modern sculptors. The exterior of the National Gallery of Art in Washington, D.C., is of Tennessee marble, and the Lincoln Memorial contains marbles from Yule, Colorado, Alabama (roof transparencies), and Georgia (Lincoln statue).Even the purest of the metamorphic marbles, such as that from Carrara, contain some accessory minerals, which, in many cases, form a considerable proportion of the mass. The commonest are quartz in small rounded grains, scales of colourless or pale-yellow mica (muscovite and phlogopite), dark shining flakes of graphite, iron oxides, and small crystals of pyrite.


Many marbles contain other minerals that are usually silicates of lime or magnesia. Diopside is very frequent and may be white or pale green; white bladed tremolite and pale-green actinolite also occur; the feldspar encountered may be a potassium variety but is more commonly a plagioclase (sodium-rich to calcium-rich) such as albite, labradorite, or anorthite. Scapolite, various kinds of garnet, vesuvianite, spinel, forsterite, periclase, brucite, talc, zoisite, wollastonite, chlorite, tourmaline, epidote, chondrodite, biotite, titanite, and apatite are all possible accessory minerals. Pyrrhotite, sphalerite, and chalcopyrite also may be present in small amounts💎💎💎



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