Mineral Commodity Profiles—Gold - USGS
gold, as distinguished from coin gold or other gold alloys. The term "karat," like "fineness," refers to purity, but purity expressed in 24ths, rather than parts per thousand; thus 24-karat gold is 1000 fine, or pure gold, and 10-karat gold refers to an alloy of gold and one or more other metals that is 10/ 24