The fusion point of gold is 1942 degrees F, and it is insoluble in acids, except aqua regia. Gold is never found pure in nature, but is always alloyed with other metals, commonly silver, copper, and iron. The farther gold travels from its source, the more pure it becomes. One troy ounce weighs 31.1035 grams, or 20 pennyweight. Our usual ounce weighs 28.350 grams.
Gold occurs primarily in high-temperature hydrothermal quartz veins in extrusive rocks.