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Desert Diary


One of the most beautiful of minerals is almost never considered when talk turns to precious and semi-precious stones. Perhaps this is because so many people know that in reality, it's only glass. Nonetheless, obsidian ranks right up there with many another natural gem. This natural glass is a result of volcanic activity and is glass rather than our usual type of lava because it has cooled rapidly—so rapidly that crystals have had no time to form.

Our desert-dwelling Native Americans knew the material well and often used it—not for decoration, but for the construction of tools. As with other glasses, obsidian breaks with a conchoidal fracture that leaves sharp edges rivaling those of the finest surgical steel tools. More importantly, unflawed obsidian gives great control to the artisan constructing arrowheads and knife blades. Scattered areas throughout the Southwest produce obsidian, and if not produced locally, river-valley deposits often contain nodules carried from upstream. Trade or travel for high quality obsidian was the norm in the past, because a horse wasn't the only Black Beauty!
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Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.



Web Resources

Mineral Galleries

USGS Obsidian Photos