igneous
Obsidian
Volcanic glass
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, typically black to dark brown in color, with a vitreous luster and conchoidal fracture.
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Physical properties
Hardness of 5 to 5.5 on the Mohs scale, typically black to dark brown in color, with a vitreous luster and conchoidal fracture.
Formation & geological history
Formed by the rapid cooling of viscous felsic lava from volcanic eruptions, lacking a crystalline structure.
Uses & applications
Used historically for sharp cutting tools and arrowheads, and presently in decorative jewelry and ornamental objects.
Geological facts
Due to its rapid cooling rate, mineral crystals do not have time to grow, resulting in a natural glass.
Field identification & locations
Easily identified by its glass-like appearance and extremely sharp edges when fractured; found near recent volcanic activity.
