igneous
Obsidian
Volcanic Glass
AI-generated identification · may be incorrectHardness of 5-5.5 on the Mohs scale, typically black or dark brown, vitreous luster, amorphous crystal structure with conchoidal fracture.
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Physical properties
Hardness of 5-5.5 on the Mohs scale, typically black or dark brown, vitreous luster, amorphous crystal structure with conchoidal fracture.
Formation & geological history
Formed from rapidly cooling felsic lava extruded from a volcano, preventing crystal growth.
Uses & applications
Historically used for sharp cutting tools and arrowheads; currently used in jewelry and decorative objects.
Geological facts
Despite being smooth and glass-like, obsidian is a naturally occurring mineraloid rather than a true mineral because it lacks a crystalline structure.
Field identification & locations
Identified by its jet-black color, glassy shine, and distinct conchoidal fracture pattern. Commonly found in regions with recent volcanic activity such as the western United States.
