Colors from ionizing radiation

All of the examples of colored minerals on this page owe their color to the effects of ionizing radiation. The changes can come from oxidation of cations (Mn2+ to Mn3+), trapped electrons (f-centers and related centers), molecular clusters often with unpaired electrons, or, as is often the case, from unknown causes 


Much beryl is heated to remove the golden to green shades that result from radiation inoder to turn the crystal into blue aquamarine.


Radiation is associated with blue and amber colors of calcite.


Naturally occuring green diamonds are colored by natural radiation. An often proposed model is that the radiation dislodges a carbon atom from the diamond structure. The resulting color center is known as the GR1 center. Many colored diamonds are also produced by laboratory irradiation. The following examples are representative.


The great diversity of colors of fluorite is mostly due to natural irradiation. Rare-earth elements in fluorite interact with radiation to produce a variety of colors.


Spodumene (variety kunzite)


Naturally occuring brown topaz is often a product of natural radiation. The color is unstable and fades in light in a matter of hours to days.


Much of the pink, manganese-containing, tourmaline in nature owes its color to natural ionizing radiation. Laboratory irradiation can essentially duplicate the color of natural tourmaline in the appropriate samples.

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last update: 12-Apr-2011