mineral
Polished black stone pendant
Likely black obsidian or black tourmaline; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectHighly polished, opaque black surface with vitreous-to-silky luster; apparent hardness is roughly Mohs 5–7, depending on material. The rounded cabochon has no visible crystal faces or cleavage; its uniform appearance may also indicate dyed or treated stone.
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Physical properties
Highly polished, opaque black surface with vitreous-to-silky luster; apparent hardness is roughly Mohs 5–7, depending on material. The rounded cabochon has no visible crystal faces or cleavage; its uniform appearance may also indicate dyed or treated stone.
Formation & geological history
If obsidian, it is volcanic glass formed by rapid cooling of silica-rich lava, generally in Quaternary volcanic environments. If tourmaline, it crystallized in pegmatites or hydrothermal veins; the image alone cannot establish geological age or composition.
Uses & applications
Used as a pendant, ornamental cabochon, or metaphysical jewelry. Obsidian is also made into blades and decorative objects; tourmaline is valued as a gemstone.
Geological facts
Black obsidian commonly shows conchoidal fracture and may reveal brown, gray, or flow banding under strong light. Black tourmaline is usually striated and crystalline rather than perfectly uniform and glassy.
Field identification & locations
Inspect the edge and any drilled hole: glassy conchoidal fracture and very sharp edges favor obsidian, while longitudinal striations and a granular crystal texture favor tourmaline. A gemological test for refractive index, specific gravity, and hardness is needed for confirmation.
