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Granite is a widely
occurring type of igneous stone.
Igneous means it is formed from magma, which is a hot,
fluid rock beneath the surface of the earth. Granites
are usually medium to coarsely crystalline. Granites
can be pink to dark gray or even black, depending on
their chemistry and mineralogy.
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The
granite peaks called the
Towers of Paine in Chile. |
Granite has many potential origins
within the earth's crust, but to be granite it must intrude
other rocks. This means that under pressure molten magma
must be forced into other rocks. The actual process that
produces granite in the earth's crust is disputed and
has led to varied schemes of classification.
Granite formations are nearly always
massive (meaning they lack internal structures), hard
and tough. As a result granite has gained widespread
use as a construction stone.
The word granite comes from the Latin
word "granum," meaning a grain. This is because of its
coarse-grained crystalline structure.
Historical Uses of Granite
The Red Pyramid of Egypt, the third largest Egyptian
pyramid, is named for the light crimson hue of its exposed
granite surfaces. The Great Pyramid of Giza contains
a huge granite sarcophagus fashioned of "Red Aswan Granite."
Because of its durability and beauty, ancient Egyptians
also used granite in high wear areas of buildings such
as to make columns, door lintels, sills, jambs, and
as wall and floor veneer.
Many large Hindu temples in southern
India, particularly those built by the 11th century
king Rajaraja Chola I, were made of granite. There is
a large amount of granite in these structures and they
are comparable to the Great Pyramid of Giza.
An unusual use of granite was for
the construction of the rails for the Haytor
Granite Tramway, in 1820 in Devon, England.
Modern Uses Of Granite
 Granite
has been extensively used as a dimension stone and as
flooring tiles in public and commercial buildings and
monuments. With increasing amounts of acid rain, granite
has begun to supplant marble as a monument material,
since it is more durable. Polished granite is also a
popular choice for kitchen
countertops due to its high durability and aesthetic
qualities.
Granite is currently known only to
exist where it forms a major part of continental crust.
Granite often occurs as relatively small, less than
100 km sq. stock masses and in batholiths that are often
associated with orogenic mountain ranges.
Granitic rock is widely distributed
throughout the continental crust of the Earth and is
the most abundant basement rock that underlies the relatively
thin sedimentary veneer of the continents. However,
since granite formations may exist as deeply as 150
miles, it is only asccessible for quarrying in limited
locations. The countries with the most commercial granite
include Finland, Norway and Sweden, Spain, Brazil, India
and several countries in southern Africa, such as Angola,
Namibia, Zimbabwe and South Africa.
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