Diamonds
The most precious gem stone is called diamond. These are mined from the ground and are cut by skilled cutters.
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Copper is also mixed in gold as an impurity which hardens the gold.
Copper
Copper is one of the few metals which can be found in the pure state in the Earth's crust. Probably for this reason, it was one of the earliest metals known to man.
It is easy to see why copper has remained one of man's most useful metals over thousands of years. It has an attractive reddish orange color. It can be easily beaten into thin sheets and complicated shapes and drawn into wire. It does not rust or wear away quickly when exposed to the weather. Jewelry, ornaments, vases, and cooking vessels are some of the objects made from copper.
Copper is particularly useful for cooking vessels because it conducts heat well. It also conducts electricity well and most copper is in fact used in the form of wiring by the electrical industry.
Copper also forms valuable alloys that is brass with zinc, and bronze with tin. Both are harder than copper. With nickel, copper forms the bright cupronickel alloys widely used for coinage.
Most copper is obtained from chalco-pyrite, or copper pyrites.
