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Marble is metamorphosed limestone, composed of fairly pure calcite (a crystalline form of calcium carbonate, CaCO3). It is extensively used for sculpture, as an building material, and in many other applicatons.
Faux marble or faux marbling is a wall painting technique that imitates the color patterns of real marble (not to be confused with paper marbling). Marble dust can be combined with cement or synthetic resins to make reconstituted or cultured marble.
A marble is also a small hard sphere used for playing games and for decoration, usually of glass or plastic but once of marble (hence its name): see marbles. This sense originates the slang marbles for testicles and, metaphorically, for courage or virility.
Places named after the stone include Marble Hill, Manhattan, New York and the town of Marble, Minnesota. The Elgin Marbles are marble sculptures taken from the Parthenon to Britain by the Earl of Elgin.
Marble comes from the shells and exoskeletons of marine animals, deposited as limestone, buried by other sediment, then melted (usually by the heat of nearby volcanic intrusions) and re-solidified. This metamorphic process turns the amorphous limestone into a mass of interlocked calcite crystals. The temperatures and pressures necessary to form marble usually destroy any fossils that may have been present in the limestone.
The characteristic swirls and veins of many colored marble varieties are usually due to various mineral impurities, originally deposited as grains or layers in the limestone, which were partially dissolved and stirred when the marble was in the molten or semi-molten state.
Some historically important kinds of marble, named after the locations of their quarries, include:
White marbles, like Carrara, have been prized for sculpture since classical times. This preference has to do with the softness and relative isotropy and homogeneity, and a relative resistance to shattering. Also, the low index of refraction of calcite allows light to penetrate several millimeters into the stone before being scattered out, resulting in the characteristic "waxy" look which gives "life" to marble sculptures of the human body.
In the construction trade, the term "marble" is used for any massive, crystalline calcitic rock (and some non-calcitic rocks) useful as building stone. For example, Tennessee Marble is really a massive, highly fossiliferous gray to pink to maroon Ordovician dolostone, known as the Holston Formation by geologists.
The word "marble" derives from the Greek marmaros, "shining stone" (OED). This stem is also the basis for the English word "marmoreal" meaning "marble-like".
As the favorite medium for Greek and Roman sculptors and architects, marble has become a cultural symbol of tradition and refined taste. Its extremely varied and colorful patterns make it a favoride decorative material, and are often imitated — e.g. in background patterns for computer displays.
In folklore, marble is associated with the astrological sign of Gemini. Pure white marble is an emblem of purity. It is also an emblem of immortality, and an ensurer of success in education.
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