Obsidian

Specimens

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  Counterclockwise from top: obsidian, pumice (lower left), and rhyolite (lower right)
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  Rainbow obsidian
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  Snowflake obsidian
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  Snowflake obsidian.
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  Pig carved in snowflake obsidian, 10 centimeters (4 in) long. The markings are spherulites.
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  from Lake County, Oregon
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  Obsidian arrowhead
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  A polished snowflake obsidian on a white background
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  A polished snowflake obsidian
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  Obsidian from Panum Crater, Mono Lake.

Formations

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  Obsidian talus at Obsidian Dome, California
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  Pile of obsidian on Newberry Obsidian flow, central Oregon
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  Glass Mountain, a large obsidian flow at Medicine Lake Volcano