igneous
Black Obsidian
Volcanic Glass (Amorphous SiO2)
AI-generated identification · may be incorrectMohs hardness 5-5.5, dark black to grey color, vitreous luster, amorphous crystal structure with conchoidal fracture.
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Physical properties
Mohs hardness 5-5.5, dark black to grey color, vitreous luster, amorphous crystal structure with conchoidal fracture.
Formation & geological history
Formed from rapidly cooling felsic lava extruded from volcanoes, 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 a mineral, obsidian is a naturally occurring volcanic glass rather than a true mineral.
Field identification & locations
Identified by its jet-black color, glass-like shine, and sharp conchoidal fracture edges; found globally near active volcanic regions.
