Triboluminescence minerals

The triboluminescence of minerals has been studied visually (see the footnotes to Table I) but only a few minerals have been examined spectroscopically. There are a few clear examples of noncentric crystals, such as quartz, whose emission is lightning, sometimes with black body radiation. Most of the triboluminescent minerals appear to have activity and color which is dependent on impurities, as is the case for kunzite, fluorite, sphalerite and probably the alkali halides. Table I attempts to distinguish between fracto-luminescence and deformation luminescence, but the distinctions are not clear cut. A detailed analysis of the structural features of triboluminescent and nontriboluminescent minerals may make it possible to draw conclusions about the nature and concentration of trace impurities that are not obvious from the color or geological site of the crystals. Triboluminescence could be used as an additional method for characterizing minerals in the field, using only the standard rock hammer, with the sensitive human eye as a detector. 

Triboluminescence, from the Greek word tribein (to rub) is a term used to describe the visible (and UV) emissions of materials when they are stressed to failure. This phenomenon is very common among minerals (see Table I), and is well known to spelunkers who enjoy smashing fluorite deposits to see the light. Earthquake lights (1) (2) are probably triboluminescence on a grand scale. 

Habit tetrahedral crystals, granular, coUoform. Color brown, yellow, orange, red, green, or black. Luster resinous, metallic, greasy. Diaphaneity transparent to opaque. Luminescence fluorescent and triboluminescent. Streak brownish white. Geavage 110. Fracture uneven, conchoidal. Twinning 111. Chemical attacked by strong mineral... 

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