igneous
Obsidian
Volcanic Glass
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, typically dark black or brown, vitreous luster, amorphous crystal structure with conchoidal fracture.
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Physical properties
Hardness of 5 to 5.5 on the Mohs scale, typically dark black or brown, vitreous luster, amorphous crystal structure with conchoidal fracture.
Formation & geological history
Formed as an extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth.
Uses & applications
Used historically for sharp tools and weapons like arrowheads, and presently for ornamental objects and surgical scalpel blades.
Geological facts
Because it cools too quickly to form a crystal structure, obsidian is technically a mineraloid rather than a true mineral.
Field identification & locations
Easily identified by its glass-like appearance and sharp conchoidal fracture edges; found near volcanic activity worldwide.
