igneous
Obsidian
Volcanic glass
AI-generated identification · may be incorrectHardness 5 to 5.5 on Mohs scale. Typically black or dark brown with a vitreous luster and distinct conchoidal fracture.
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Physical properties
Hardness 5 to 5.5 on Mohs scale. Typically black or dark brown with a vitreous luster and distinct conchoidal fracture.
Formation & geological history
Formed as an extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth.
Uses & applications
Used historically for sharp cutting tools and arrowheads, and currently in decorative objects and surgical scalpel blades.
Geological facts
Ancient civilizations widely traded obsidian across continents for weapon manufacturing due to its extremely sharp edges.
Field identification & locations
Identify by its glass-like appearance, smooth curved fracture surfaces, and complete lack of visible crystal grains.
