The Colors of Minerals

This page presents information about the causes of color in minerals and provides illustrations of many examples. The common causes are metal ions, intervalence charge transfer, ionizing radiation, physical effects, and band gaps. 
1) Metal ions cause the color of many common and uncommon minerals.

Click here to investigate a list of metal ions to see the colors they cause in different minerals.

2) Intervalence Charge Transfer, involving metal ions in mixed oxidation states is another important factor in the coloration of minerals. Most commonly, we encounter minerals with the Fe2+ - Fe3+ interaction and with the Fe2+ - Ti4+ interaction.

For many examples, follow this link. 

3) Colors from natural ionizing radiation are frequently encountered in nature. 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.

4) 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.

5) Semiconducting minerals have band gaps which often result in intense colors.   Numerous sulfides are examples of this.

Click here to see examples.

For more information of the colors of specific minerals groups go the the appropriate mineral on the list of mineral spectra


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