igneous
Obsidian
Volcanic glass
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, dark black or dark brown 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, dark black or dark brown color, vitreous luster, amorphous crystal structure with conchoidal fracture.
Formation & geological history
Formed as extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth.
Uses & applications
Used historically for cutting tools and arrowheads, and currently in decorative jewelry and surgical scalpel blades.
Geological facts
Due to its rapid cooling, it lacks a crystalline structure and is technically a mineraloid rather than a true mineral.
Field identification & locations
Identified by its glass-like appearance, smooth curved conchoidal fractures, and sharp edges; commonly found in areas of recent volcanic activity.
