It has been used by mankind for thousands of years, and is still widely used today in a variety of fields ranging from from decoration to economics, to medical and industrial technology. The chemical symbol for gold is Au. It's composition is usually pure gold, but it may sometimes form alloys with silver , copper , or other metals. An alloy of silver and gold with an intermediate composition is called electrum. This property results from the response of the eye to the visible part of the electromagnetic spectrum.
Pure gold appears as gold-yellow.
When alloyed with silver, it is a lighter color than pure gold When alloyed with copper, gold has a reddish color. This property describes the quality of light reflected off the mineral. Gold has a metallic luster. This is the color of the powdered mineral. The streak of gold is the same as its color.