The recognition of colors in minerals goes back to our pre-historic ancestors who used charcoal and iron oxides to color cave paintings which still retain their original intensity. The color is a constant and predictable component of the mineral. Examples are blue Azurite, red Cinnabar, and green Malachite. In this case, the color is a variable and unpredictable property of the mineral. In these cases, color is variable but a unique property of the mineral.
Examples are the colors produced by precious opal and the shiller reflections of labradorite.
Table of mineral colors linked to mineral lists.