igneous
Obsidian
Volcanic Glass
AI-generated identification · may be incorrectMohs hardness of 5 to 5.5, typically black or dark brown in color with a vitreous luster. Features conchoidal fracture and an amorphous crystal structure.
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Physical properties
Mohs hardness of 5 to 5.5, typically black or dark brown in color with a vitreous luster. Features conchoidal fracture and an amorphous crystal structure.
Formation & geological history
Formed as extrusive igneous rock from rapidly cooling felsic lava without crystal growth. Found globally in areas with recent volcanic activity.
Uses & applications
Used historically for sharp cutting tools and arrowheads, and currently in decorative objects, jewelry, and specialized surgical scalpels.
Geological facts
Despite lacking a true crystal lattice, obsidian is classified as a mineraloid rather than a true mineral. Ancient civilizations traded it extensively across vast distances for weaponry.
Field identification & locations
Identified easily by its shiny, glass-like appearance and extremely sharp curved edges when fractured. Common locations include the western United States, Mexico, and Italy.
