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Obsidian - Wikipedia, the free encyclopedia
Obsidian is a naturally occurring volcanic glass formed as an extrusive igneous rock. It is produced when felsic lava extruded from a volcano cools without crystal growth.
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Obsidian.net is the home for Obsidian Entertainment, developer of Neverwinter Nights 2, Star Wars Knights of the Old Republic II, Alpha Protocol and Aliens RPG
Obsidian use in Mesoamerica - Wikipedia, the free encyclopedia
Obsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica. Obsidian was a highly integrated part of daily and ...

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Obsidian, dark, semitranslucent volcanic glass of the same composition as rhyolite, produced when molten igneous rock (magma) pushes its way up to the earth's surface and cools so rapidly that its constituent ions do not have time to crystallize. Obsidian is usually black, but may also be red or brown. Because it is easy to shape by flaking, it was prized by early peoples, who used it to make weapons and tools. See Lava.

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