Gold

Gold is ductile, malleable, corrosion-resistant, non-toxic, biologically inert, wears well, does not degrade, and is a superior conductor of electricity.   Because gold is a soft metal, it is often alloyed to give it more strength.   Gold was always used for jewelry; formerly, it was used extensively in coinage.   However, in addition to these well-known uses, gold has many industrial applications:   The most important use of gold is as the extremely small wire conductors and connectors ("jacks") in electrical and electronic circuits in semiconductors, microprocessors, and printed circuit boards (PCBs) to assure consistently clean, corrosion-free contacts and reliable signals. ^{Gold n.p.}   Gold is used for highly reflective mirrors in telescopes, copy machines, satellites, aircraft engines and security systems. ^{Gold n.p.}   Gold alloyed with other metals is used in dentistry as tooth fillings, lagophthalmos (inability to fully close the eyelid) correction, gold vapor lasers to destroy cancer cells, pellets to clean clogged arteries, salts to treat rheumatoid arthritis, and quick-acting wave guide thermometers. ^{Gold n.p.}

Gold was known to the ancients and prized for its value, as it is today.   Gold is found as a pure metal and in tellurides (tellurium & gold), and it is usually found associated with quartz and pyrite minerals.   Gold is isolated from its ores by cyaniding, amalgamating and smelting.   Refining is by electrolysis. ^{Lide 4-13}