Thursday, February 12, 2009

Silver

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Silver Coin

Silver is somewhat rare and expensive, although not as expensive as gold. Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate silver from lead as early as 3000 B.C. Pure silver has a brilliant white metallic lustre. It is a little harder than gold and is very ductile and malleable. Pure silver has the highest electrical and thermal conductivity of all metals, and possesses the lowest contact resistance. Silver iodide, AgI, is (or was?) used for causing clouds to produce rain.

Silver is stable in pure air and water, but tarnishes when exposed to ozone, hydrogen sulphide, or air containing sulphur. It occurs in ores including argentite, lead, lead-zinc, copper and gold found in Mexico, Peru, and the USA.