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
1) Metal ions cause the color of many common and uncommon
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+
For many examples, follow this
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
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
to the index of data files
to the Mineral Spectroscopy home page