igneous
Obsidian
Volcanic Glass
AI-generated identification · may be incorrectHardness of 5 to 5.5 on the Mohs scale, typically jet black with a vitreous luster, amorphous crystal structure, and sharp conchoidal fracture.
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Physical properties
Hardness of 5 to 5.5 on the Mohs scale, typically jet black with a vitreous luster, amorphous crystal structure, and sharp conchoidal fracture.
Formation & geological history
Formed as extrusive igneous rock when felsic lava cools rapidly with minimal crystal growth, commonly associated with rhyolitic volcanic eruptions.
Uses & applications
Historically used for making cutting tools, arrowheads, and spear points, and modernly utilized in surgical scalpels and ornamental jewelry.
Geological facts
Due to its extremely sharp edges when fractured, obsidian blades can be significantly sharper than high-quality steel surgical scalpels.
Field identification & locations
Easily identified by its glassy appearance, smooth conchoidal fracture patterns, and deep black coloration, frequently found in regions with recent volcanic activity.
