igneous
Obsidian
Volcanic glass
AI-generated identification · may be incorrectHardness 5-5.5 on Mohs scale, black or dark brown color, vitreous luster, amorphous crystal structure with conchoidal fracture, specific gravity around 2.4.
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Physical properties
Hardness 5-5.5 on Mohs scale, black or dark brown color, vitreous luster, amorphous crystal structure with conchoidal fracture, specific gravity around 2.4.
Formation & geological history
Formed from rapidly cooling felsic lava extruded from a volcano, lacking time for crystal growth. Typically associated with rhyolitic eruptions.
Uses & applications
Historically used for making sharp cutting tools, arrowheads, and blades. Today used in surgical scalpels, jewelry, and ornamental items.
Geological facts
Obsidian has been traded and utilized by humans since the Stone Age for its exceptionally sharp edges, which can be finer than modern steel blades.
Field identification & locations
Easily identified by its glassy appearance, conchoidal fracture, and dark translucent edges. Found worldwide in areas with past volcanic activity.
