igneous
Obsidian
Volcanic glass
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, black to dark brown color, vitreous luster, and conchoidal fracture.
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Physical properties
Hardness of 5 to 5.5 on the Mohs scale, black to dark brown color, vitreous luster, and 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, arrowheads, and blades; currently used in jewelry and decorative objects.
Geological facts
Despite looking like a mineral, obsidian is actually a mineraloid because it lacks a crystalline structure.
Field identification & locations
Easily identified by its glass-like appearance, smooth curved fracture surfaces, and sharp edges; found near recent volcanic activity worldwide.
