igneous
Black Obsidian
Volcanic Glass (Silica glass with magnetite/hematite microcrystals)
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, deep 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, deep black 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 widely for ornamental carvings, jewelry, metaphysical tools, and historically for sharp cutting blades.
Geological facts
Obsidian cools so fast that crystal structures cannot form, resulting in a natural glass with extremely sharp edges.
Field identification & locations
Easily identified by its glass-like luster, conchoidal fracture patterns, and deep opaque black color.
