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. This is a measure of the mineral's resistance to scratching. Gold has a hardness of 2.5 - 3 on Moh's scale of hardness . Cleavage This is the property of a mineral to break along planar, crystallographically controlled surfaces.