igneous
Obsidian
Volcanic Glass
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, deep black color, vitreous luster, amorphous crystal structure, and exhibits conchoidal fracture.
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Physical properties
Hardness of 5 to 5.5 on the Mohs scale, deep black color, vitreous luster, amorphous crystal structure, and exhibits conchoidal fracture.
Formation & geological history
Formed from rapidly cooling felsic lava extruded from a volcano, preventing crystal growth.
Uses & applications
Used historically for cutting tools and arrowheads, and currently in decorative objects and surgical scalpel blades.
Geological facts
Obsidian lacks a true crystal structure because it cools too quickly for minerals to crystallize, classifying it as a mineraloid.
Field identification & locations
Easily identified by its glassy appearance, sharp conchoidal edges, and opaque black color. Found worldwide in regions with recent volcanic activity.
