mineral
Polished black stone, likely shungite
Shungite; carbon-rich mineraloid composed mainly of amorphous carbon, with silica and other minerals
AI-generated identification · may be incorrectBlack, opaque, glassy to submetallic luster, smooth polished surface, and conchoidal fracture; Mohs hardness about 3.5–4, with variable density and composition. The rounded triangular shape is human-cut and polished.
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Physical properties
Black, opaque, glassy to submetallic luster, smooth polished surface, and conchoidal fracture; Mohs hardness about 3.5–4, with variable density and composition. The rounded triangular shape is human-cut and polished.
Formation & geological history
Shungite formed in Precambrian sedimentary rocks, especially the ~2.0-billion-year-old deposits of Karelia, Russia, from carbon-rich organic material altered during diagenesis and low-grade metamorphism.
Uses & applications
Used for ornamental carvings, cabochons, jewelry, decorative objects, and occasionally industrial carbon products; purported healing or water-purification claims are not well supported scientifically.
Geological facts
The specimen’s black color and scattered pits are consistent with polished shungite, but the photograph alone cannot exclude black tourmaline, obsidian, basalt, or dyed stone.
Field identification & locations
Field identification requires locality, streak, hardness, density, and ideally carbon/mineral analysis; genuine shungite is strongly associated with Karelia and commonly leaves a dark streak. The triangular cabochon is likely a low-grade decorative piece.
