Most common minerals have had a long history of exposure to ionizing radiation from natural radiation sources in rocks. A variety of minerals can also be colored by artificial irradiation which enter the commercial market in the form of colored gemstones. Follow this link to examples of radiation coloration in minerals. Physical effects such as diffraction also cause colors in minerals. The color of gem opal is the result of diffraction as is the color of certain crystals of labradorite feldspar.
Examples are available here .
Numerous sulfides are examples of this. Click here to see examples.