Marble is a non-foliated metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Geologists use the term «marble» to refer to metamorphosed limestone; however, stonemasons use the term more broadly to encompass unmetamorphosed limestone. Marble is commonly used for sculpture and as a building material.
The word «marble» derives from the Greek «μάρμαρον» (mármaron), from «μάρμαρος» (mármaros), «crystalline rock», «shining stone», perhaps from the verb «μαρμαίρω» (marmaírō), «to flash, sparkle, gleam». This stem is also the basis for the English word marmoreal, meaning «marble-like.»
Whilst the English term resembles the French marbre, most other European languages (e.g. Spanish mármol, Italian marmo, Portuguese mármore, German, Norwegian, Danish and Swedish marmor, Persian and Irish marmar, Dutch marmer, Polish marmur, Turkish mermer, Czech mramor and Russian мрáмор) follow the original Greek.
Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonly limestone or 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 crystals. 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-poor) limestone or dolomite protolith. 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.
White marble has been prized for its use in sculptures since classical times. This preference has to do with its softness, 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 any kind.
Construction marble[edit source | editbeta]
Construction marble is a stone which is composed of calcite, dolomite or serpentine which is capable of taking a polish. More generally in 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. For example, Tennessee marble is really a dense granular fossiliferous gray to pink to maroon Ordovician limestone that geologists call the Holston Formation.
According to the United States Geological Survey, U.S. dimension marble production in 2006 was 46,400 tons valued at $18.1 million, compared to 72,300 tons valued at $18.9 million in 2005. Crushed marble production (for aggregate and industrial uses) in 2006 was 11.8 million tons valued at $116 million, of which 6.5 million tons was finely ground calcium carbonate and the rest was construction aggregate. For comparison, 2005 crushed marble production was 7.76 million tons valued at $58.7 million, of which 4.8 million tons was finely ground calcium carbonate and the rest was construction aggregate. U.S. dimension marble demand is about 1.3 million tons. The DSAN World Demand for (finished) Marble Index has shown a growth of 12% annually for the 2000–2006 period, compared to 10.5% annually for the 2000–2005 period. The largest dimension marble application is tile.
Marble production is dominated by 4 countries that account for almost half of world production of marble and decorative stone. Italy is the world leader in marble production, with 20% share in global marble production followed by China with 16% of world production. India is third ranking with 10% of world production, followed by Spain in fourth ranking position with 6% of world production. The other marble producing countries of the world represent the remaining other half of world marble production.
Marble dust is combined with cement or synthetic resins to make reconstituted or cultured marble. The appearance of marble can be simulated with faux marbling, a painting technique that imitates the stone’s color patterns.
As the favorite medium for Greek and Roman sculptors and architects (see classical sculpture), marble has become a cultural symbol of tradition and refined taste. Its extremely varied and colorful patterns make it a favorite decorative material, and it is often imitated in background patterns for computer displays, etc.
Places named after the stone include Marblehead, Ohio; Marblehead, Massachusetts; Marble Arch, London; the Sea of Marmara; India’s Marble Rocks; and the towns of Marble, Minnesota; Marble, Colorado; Marble Falls, Texas, and Marble Hill, Manhattan, New York. The Elgin Marbles are marble sculptures from the Parthenon that are on display in the British Museum. They were brought to Britain by the Earl of Elgin.