igneous
Black Obsidian
Volcanic Glass (Amorphous SiO2)
AI-generated identification · may be incorrectMohs hardness 5-5.5, jet black color, vitreous luster, amorphous crystal structure, conchoidal fracture, specific gravity 2.35-2.60.
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Physical properties
Mohs hardness 5-5.5, jet black color, vitreous luster, amorphous crystal structure, conchoidal fracture, specific gravity 2.35-2.60.
Formation & geological history
Formed from rapidly cooling felsic lava where crystal growth is inhibited, typically in continental volcanic environments.
Uses & applications
Used for decorative carvings, polished spheres, jewelry, and historically for sharp cutting tools like arrowheads.
Geological facts
Obsidian lacks a true crystal lattice and is technically a mineraloid rather than a mineral.
Field identification & locations
Identified by its shiny, smooth black appearance and characteristic conchoidal fracture edges; found worldwide near volcanic regions.
