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You are browsing the archive for 2 November 2010 - Mountain Beltway.

2 November 2010

That’s what you call a conchoidal fracture

Obsidian bearing well-developed conchoidal (clam-shell-shaped) fracture with concentric ribs, as displayed at the recent U.S. Science and Engineering Festival on the National Mall by a local gem/fossil/mineral club.

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