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OTHER ITA SITES:
The Hidden History of Gold
Gold is a pure metal first found by early man. It is very workable in its naturally occurring pure state and has been used by craftsmen for the past 11,000 years.
Revered for millennia gold is now the material of choice of people across the globe as an expression of love. Letís look more closely at the fascinating story of gold.
The chemical element gold has atomic number 79 and its chemical symbol is Au from the Latin aurum. Soft, lustrous yellow it is a malleable metal. Gold is known as one of the transition metals and its atomic weight is 196.967, and it belongs to group 1B in the periodic table along with copper and silver.
Gold is commonly alloyed with other metals. In jewelry varying proportions of other metals are added to yield the desired hardness and color. For example, an alloy of gold, silver, and copper in which silver predominates is called "green gold."
An alloy of the same three elements in which copper predominates is called "red gold" and an alloy of gold and nickel is called "white gold."
The purity of alloyed gold is expressed by the karat system. In this system the percent of gold by weight is given as a fraction of 24. Thus pure gold is 24 karat (.999), 18-karat gold is 18/24, or 75% (.750) and 14-karat gold is 14/24, or 58% (.584).
The melting point of pure gold is 1,063 deg. C and its boiling point is 2,966 deg. C. In addition to its softness, gold is both the most malleable and most ductile of metals. It can be hammered into extremely thin sheets (approaching a small number of atoms) and can be drawn into extremely fine wire. Gold in the form of very thin sheets, called gold leaf, has many decorative uses.
The Earth's crust averages a mere 0.004 grams of gold per ton and commercial concentrations of gold are found in areas distributed widely over the globe.
Gold occurs in association with ores of copper and lead, in quartz veins, in the gravel of stream beds, and with pyrites (iron sulfide).
Distribution of Gold Around the World
Seawater contains quantities of gold but the process of recovering gold from the sea is not economical. The ancients found quantities of gold in Ophir, Sheba, Uphaz, Parvaim, Arabia, India, and Spain. By the first century AD, written reports were made of deposits in Thrace, Italy, and Anatolia. Gold is also found in Wales, in Hungary, in the Ural Mountains of Russia, and, in large quantities, in Australia.
The greatest early surge in the mining of gold followed the first voyage of Columbus. From 1492 to 1600, Central and South America, Mexico, and the islands of the Caribbean Sea contributed significant quantities of gold to world commerce.
Colombia, Peru, Ecuador, Panama, and Hispaniolacontributed 61% of the world's newfound gold during the 17th century and in the 18th century they supplied 80%.
After the discovery of gold in California in 1848, North America became the world's major supplier of the metal. From 1850 to 1875 more gold was discovered than in the previous 350 years. By 1890 the gold fields of Alaska and the Yukon edged out those in the western United States, and soon the African Transvaal exceeded even these. The world's current unmined reserves are estimated at one billion troy oz (31 billion g), with about half of this in the Witwatersrand area of the Republic of South Africa.
The widespread distribution of gold validates the theory that gold was carried toward the Earth's surface from great depths by geologic activity, perhaps with other metals as a solid solution within molten rock. After this solid solution cooled, gold content was spread through such a great volume of rock that large fragments were unusual.
This theory explains why the world's gold is in small, often microscopic particles.
It also explains why small amounts of gold are widespread in all igneous rocks.
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