Monday 22 August 2011

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An irregularly shaped rock, milky-white in color. The rock glistens or sparkles from the overhead lights.
Marble.
Folded and weathered marble atGeneral Carrera LakeChile.
The Taj Mahal is made of marble.
Natural patterns on the polished surface of Breccia or "landscape marble" can resemble a city skyline or even trees, and were used as inlays for furniture etc.
Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonlycalcite or dolomite.
Geologists use the term "marble" to refer to metamorphosed limestone; however stonemasons use the term more broadly to encompass unmetamorphosed limestone.[1]
Marble is commonly used for sculpture and as a building material.

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[edit]Etymology

The word "marble" derives from the Greek "μάρμαρον" (mármaron),[2] from "μάρμαρος" (mármaros), "crystalline rock", "shining stone",[3][4] perhaps from the verb "μαρμαίρω" (marmaírō), "to flash, sparkle, gleam".[5] 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. SpanishmármolItalian marmoPortuguese mármoreGermanNorwegian and Swedish marmorDutchmarmerPolish marmurTurkish mermerCzech mramor and Russian мрáмор ) follow the original Greek.

[edit]Physical origins

Marble is a rock resulting from metamorphism of sedimentary carbonate rocks, most commonlylimestone 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 claysiltsandiron 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.

[edit]Types

Examples of historically notable marble varieties and locations:
Marble nameColorLocationCountry
Bucova Marblewhite, grayBăuţar, Caraş-Severin County (applied in Ulpia Traiana Sarmizegetusa)Romania
Carrara marblewhite or blue-grayCarraraItaly
Connemara marblegreenConnemaraIreland
Creole marblewhite and blue/blackPickens County, GeorgiaUnited States
Ziarat White marblePure whiteZiarat RegionPakistan
Badal marbleGrey, Grayish whiteNWFP, BaluchistanPakistan
Boticena marbleVarious Colors and TexturesNWFP, BaluchistanPakistan
Etowah marblepink, salmon, rosePickens County, GeorgiaUnited States
Macael marblewhiteMacaelAlmeriaSpain
Makrana MarblewhiteMakranaIndia
Murphy MarblewhitePickens and Gilmer Counties, GeorgiaUnited States
Parian marblepure-white, fine-grainedIsland of ParosGreece
Pentelic marble[6]pure-white, fine-grained semitranslucentPenteliko MountainAthensGreece
Phrygian MarblepurplePhrygiaTurkey
Purbeck MarbleGrey/BrownIsle of PurbeckUnited Kingdom
Ruskeala Marblewhitenear Ruskeala, KareliaRussia
Sienese Marbleyellow, yellowish-whitenear Sovicille, TuscanyItaly
Bianco Sivecwhitenear PrilepRepublic of Macedonia
Sylacauga marblewhiteTalladega County, AlabamaUnited States
Tennessee marblepale pink to cedar-redKnoxBlount and Hawkins CountiesTennesseeUnited States
Vermont MarblewhiteProctor, VermontUnited States
Yule Marbleuniform pure whitenear Marble, ColoradoUnited States
Wunsiedel MarblewhiteWunsiedel, BavariaGermany

[edit]Uses

[edit]Sculpture

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 the human body.

[edit]Construction marble

Construction marble is a stone which is composed of calcite, dolomite or serpentine which is capable of taking a polish.[7] More generally inconstruction, 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.

[edit]Production

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.

[edit]Artificial marble

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.

[edit]Cultural associations

Marble from Italy.
Ancient marble columns in the prayer hall of the Mosque of Uqba, in KairouanTunisia
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,OhioMarblehead, MassachusettsMarble Arch, London; the Sea of Marmara; India's Marble Rocks; and the towns of Marble, MinnesotaMarble, Colorado; andMarble Hill, Manhattan, New York. The Elgin Marblesare marble sculptures from the Parthenon that are on display in the British Museum. They were brought to Britain by the Earl of Elgin.

[edit]See also

[edit]References

  1. ^ Kearey, Philip (2001). Dictionary of Geology, Penguin Group, London and New York, p. 163. ISBN 978-0-14-051494-0
  2. ^ μάρμαρον, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
  3. ^ μάρμαρος, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
  4. ^ Marble, Compact Oxford English Dictionary
  5. ^ μαρμαίρω, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
  6. ^ http://www.britannica.com/EBchecked/topic/450431/Pentelic-marble
  7. ^ Marble Institute of America pp. 223 Glossary

[edit]External links

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