igneous
Obsidian
Volcanic Glass (Silica, SiO2)
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, jet black color, vitreous luster, amorphous crystal structure with conchoidal fracture.
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Physical properties
Hardness of 5 to 5.5 on the Mohs scale, jet black color, vitreous luster, amorphous crystal structure with conchoidal fracture.
Formation & geological history
Formed through the rapid cooling of felsic lava associated with volcanic eruptions, lacking time for crystal growth.
Uses & applications
Used historically for sharp cutting tools and arrowheads, and presently in ornamental jewelry and surgical scalpel blades.
Geological facts
Obsidian fractures with extremely sharp edges, often forming fragments thinner than the edge of a steel razor.
Field identification & locations
Identified by its glossy, glass-like appearance and sharp conchoidal fracture edges; commonly found near recent volcanic activity.
