SILVER 4000BC TILL TODAY HISTORY AND FACTS

2009-11-20 11:20:14
Silver was discovered after gold and copper somewhere in the year 4000 BC,

Silver production history and facts Silver was discovered after gold and copper somewhere in the year 4000 BC, when it was used in jewelry and as a medium of exchange, just as we use money today. The earliest known working mines of medium size were those of the pre-Hittites of Cappadocia in eastern Anatolia. Silver is generally found in the combined state in nature, usually in Copper or lead mineralization, and by 2000 BC mining and smelting of silver-bearing lead ores were well under way. Lead ores were smelted to obtain an impure lead-silver alloy, which was then fire refined by cupellation. The best-known of the ancient mines were located at the Laurium silver-lead deposit in Greece; this was actively mined from 500 BC to AD 100. Spanish mines were also a major source of silver production. By the 16th century, Spanish conquistadores had discovered and developed silver mines in Mexico, Bolivia, and Peru. These mineral deposits where rich in silver, resulting in the rise of South and Central America as the largest silver-producing areas in the world. For the recovery of pure silver from these mines, the Patio process was employed. Silver-bearing ore was ground and mixed with salt, roasted copper ore, and mercury. The mixing was accomplished by tethering mules to a central post on a paved patio (hence the name of the process) and compelling them to walk in a circle through the mixture. The silver was gradually converted to the elemental state in a very finely divided form, from which it was dissolved by the mercury. Periodically, the mercury was collected and distilled to recover the silver, and was subsequently refined by cupellation. Cyanidation processes supplanted the Patio process in the late 19th century; by that time, the Moebius and Balbach electro refining processes had been introduced. In the mid-19th century a large silver deposit was discovered in Nevada. This resulted in the United States becoming the world's largest silver producer until the 20th century, when it was surpassed by Mexico and South America (particularly Peru).