igneous
Obsidian
Volcanic Glass
AI-generated identification · may be incorrectMohs hardness 5 to 5.5, jet black color, vitreous luster, amorphous crystal structure, conchoidal fracture, specific gravity around 2.4.
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Physical properties
Mohs hardness 5 to 5.5, jet black color, vitreous luster, amorphous crystal structure, conchoidal fracture, specific gravity around 2.4.
Formation & geological history
Formed as 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 jewelry and ornamental objects.
Geological facts
Despite its glass-like appearance, it is a naturally occurring mineraloid rather than a true mineral.
Field identification & locations
Easily identified by its glass-like sheen and sharp conchoidal fracture edges; found near volcanic regions worldwide.
