Post 477 –by Gautam Shah
Copper resources of the world are estimated at nearly 5.8 trillion pounds. Of these only about 0.7 trillion pounds have been mined to date. The recycling and recovery rates of copper are so high that of nearly all of the copper mined throughout history, is still in circulation today. This means nearly 80 % of all copper ever mined is still in use today.
Copper was discovered by prehistoric man, in search of shiny stones that when beaten did not break down but rather flattened out. This was sensational discovery leading to search of shiny nodules across lands. Pure Gold and Copper nodules were forged into items of adornments and tools. It was known that several nodules of such pure metals could be forged to form a larger piece. Such nodule findings were rare. But two forms of copper carbonates greenish malachite and bluish azurite were easy to identify and collect from the grounds. Malachite was also used as a gemstone. Similarly many other bright minerals were identified.
Copper was known around 10000 BC or even earlier. Earliest copper object, a pendant dating 8700 BC, was found Iraq. Copper, in natural nodules form, remained a prized material for a while, but soon became a metal of utility. Unalloyed copper is soft for tools and weapons, but fairly suitable for shaping of utensils. Mesopotamia and Egypt exploited copper for creating tools used in farming, wood working, cooking, etc. These were hoes, adzes, saws, combs , pots, dishes, chisels, harpoons, cloak-pins etc. By 6000 BC it was realized that, although copper was not amenable to casting, it could be worked by hammering, chasing, engraving, and cold-rolling. Sumerians used copper sheets to form sculptures over wooden forms and fastened on walls with copper nails or wires set in bitumen.
The Roman supply of copper almost entirely came from Cyprus, and so was known as metal of Cyprus, shortened to cyprium, later corrupted to cuprum. Copper is found at many locations as a primary mineral in basaltic lavas and also as reduced form of copper compounds. It occurs in combination with many minerals, such as chalcocite, chalcopyrite, bornite, cuprite, malachite, and azurite. It is an extremely ductile and malleable metal with high tensile strength. It is an excellent conductor of heat and electric. It is a very noble metal and by acting as a cathode can corrode other contagious metals except stainless steel. It is resistant to most acids and sea water.
A Copper alloy with tin is known as bronze. Bronze is a stronger alloy, and harder than both the pure metals. Bronze can be cast. A copper with zinc is called Brass. It was also known that by hammering the copper became hardened, ideal for creation hard edged tools. Copper and its alloys, bronze and brass, mark the first science revolution of man. However, relative scarcity of tin in many regions of the world did not allow use Bronze equally everywhere. Tin-based bronzes were preferred due to the hazard of arsenic poisoning from fumes produced by the oxidation of arsenic-containing minerals. Copper-arsenic alloys, of superior properties to copper in both cast and wrought form, were produced in many regions. Arsenic contents varied from 1 to 7 percent, with up to 3 percent tin. In many civilizations the production of pure copper, arsenical copper, and tin bronze continued together for some time.