Everything about Marble totally explained
Marble is a nonfoliated
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, 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.
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.
Places named after the stone include
Marblehead,
Ohio;
Marble Arch,
London; the
Sea of Marmara;
India's
Marble Rocks; and the towns of
Marble, Minnesota;
Marble, Colorado; 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.
Etymology
The word "marble" derives from the
Greek μάρμαρον (
marmaron) and that from
μάρμαρος (
marmaros), "crystalline rock", "shining stone", perhaps from the verb
μαρμαίρω (
marmairō), "to flash, sparkle, gleam". This stem is also the basis for the English word "marmoreal" meaning "marble-like".
Origins
Marble is a
metamorphic rock resulting from regional or rarely contact
metamorphism of
sedimentary carbonate rocks, either
limestone or
dolostone, or metamorphism of older marble. This metamorphic process causes a complete recrystallization of the original rock into an interlocking mosaic of
calcite,
aragonite and/or
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 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.
Types of marble
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Some historically important kinds of marble, named after the locations of their
quarries, include
White marbles, like Carrara in Italy, Royal White and Beijing White in China, 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.
Construction marble
In the
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.
Industrial use of marble
Colorless or light-colored marbles are a very pure source of
calcium carbonate, which is used in a wide variety of industries. Finely ground marble or calcium carbonate powder is a component in
paper, and in consumer products such as
toothpaste,
plastics, and
paints. Ground calcium carbonate can be made from limestone, chalk, and marble; about three-quarters of the ground calcium carbonate worldwide is made from marble. Ground calcium carbonate is used as a coating pigment for paper because of its high brightness and as a paper filler because it strengthens the sheet and imparts high brightness. Ground calcium carbonate is used in consumer products such as a food additive, in toothpaste, and as an inert filler in pills. It is used in plastics because it imparts stiffness, impact strength, dimensional stability, and thermal conductivity. It is used in paints because it's a good filler and extender, has high brightness, and is weather resistant. However, the growth in demand for ground calcium carbonate in the last decade has mostly been for a coating pigment in paper.
Calcium carbonate can also be reduced under high heat to
calcium oxide (also known as "lime"), which has many applications including being a primary component of many forms of
cement.
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.
Cultural associations
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's often imitated in background patterns for
computer displays, etc.
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 insurer of success in education.
Further Information
Get more info on 'Marble'.
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