mineral

Tumbled smoky quartz (probable)

Quartz, silicon dioxide (SiO₂), smoky variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent dark brown to gray, with vitreous luster and conchoidal fracture. Quartz is trigonal and lacks cleavage; the smooth surface indicates tumbling and polishing.

Identified August 16, 2026More mineral →

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Physical properties

Hardness 7 Mohs; translucent dark brown to gray, with vitreous luster and conchoidal fracture. Quartz is trigonal and lacks cleavage; the smooth surface indicates tumbling and polishing.

Formation & geological history

Smoky color generally results from natural or irradiation-induced color centers associated with trace aluminum during crystallization in granitic pegmatites, hydrothermal veins, or cavities. Geological ages vary widely, commonly Paleozoic to Precambrian host-rock settings.

Uses & applications

Used as a decorative tumbled stone, cabochon, ornament, and collector specimen; quartz is also important in glass, electronics, and ceramics. This example appears primarily ornamental rather than gem-grade.

Geological facts

The apparent central seam may be a fracture, growth boundary, or polishing feature; image-only identification is not definitive. A glass imitation would usually lack quartz’s characteristic hardness and natural internal irregularities.

Field identification & locations

Common sources include Brazil, Madagascar, Switzerland, Spain, and the United States. Confirm with a scratch test against ordinary glass (quartz should scratch it), though testing may damage the specimen; avoid confusing it with obsidian, which is softer and more uniformly glassy.