igneous
Black Obsidian (Faceted)
Volcanic Glass (Amorphous Silicon Dioxide)
Hardness: 5-5.5 (Mohs), Color: Pitch black to smoky brown translucent, Luster: Vitreous/Glassy, Structure: Amorphous (no crystal structure), Cleavage: None (conchoidal fracture), Specific Gravity: 2.35-2.6
- Hardness
- 5-5
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Physical properties
Hardness: 5-5.5 (Mohs), Color: Pitch black to smoky brown translucent, Luster: Vitreous/Glassy, Structure: Amorphous (no crystal structure), Cleavage: None (conchoidal fracture), Specific Gravity: 2.35-2.6
Formation & geological history
Formed by the rapid cooling of silica-rich felsic lava, which prevents crystal growth. It is found in volcanic regions of various ages, typically associated with rhyolitic eruptions.
Uses & applications
Used in jewelry, decorative carvings, metaphysical tools, and historically for ultra-sharp surgical-grade blades and arrowheads.
Geological facts
Obsidian is technically a glass rather than a true mineral because it lacks a crystalline structure. It was one of the first materials traded extensively by ancient civilizations for tool-making.
Field identification & locations
Identify by its deep black color, glassy sheen, and sharp edges. This specimen is faceted into a hexagonal/geometric shape. Commonly found in Iceland, Mexico, and the Western United States.
