igneous
Obsidian
Volcanic glass
AI-generated identification · may be incorrectHardness 5 to 5.5 on Mohs scale, black to dark brown color, vitreous luster, conchoidal fracture with no true crystal structure.
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Physical properties
Hardness 5 to 5.5 on Mohs scale, black to dark brown color, vitreous luster, conchoidal fracture with no true crystal structure.
Formation & geological history
Formed from rapidly cooling felsic lava extruded from a volcano, preventing crystal growth.
Uses & applications
Used historically for sharp cutting tools and arrowheads, and currently in jewelry and ornamental carvings.
Geological facts
Despite looking like modern man-made glass, obsidian is completely natural and has been utilized by humans for millions of years.
Field identification & locations
Easily identified by its extremely sharp edges, smooth glassy texture, and distinct conchoidal fracture pattern.
