Materials
Obsidian
Volcanic Glass
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A naturally occurring volcanic glass, an igneous rock formed when felsic lava cools so rapidly that mineral crystals barely form. The high silica content of the rhyolitic flows it comes from makes the lava so viscous that atoms cannot arrange into crystals, and rapid cooling finishes the job, leaving a natural glass whose conchoidal fracture gave prehistory its sharpest cutting edges.
Facts
Formation ClassIgneous, extrusive (volcanic glass formed when lava cools rapidly with minimal crystal growth) 1 Cross-Tradition Connections
Caused By
Formed when lava extruded from a volcano cools rapidly with minimal crystal growth.
In Discipline
Sources
1. Obsidian (Wikipedia)
Wikimedia FoundationLead sectionQuote, Lead section
Obsidian is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock.
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