mineral

Tumbled smoky quartz (probable)

Quartz, silicon dioxide (SiO₂), smoky variety

AI-generated identification · may be incorrect

A small polished/tumbled stone with translucent brown to gray-purple color and vitreous luster. Quartz has hardness 7, a hexagonal crystal structure, indistinct cleavage, and specific gravity about 2.65; the image alone cannot confirm the variety.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Smoky quartz forms when natural or radiation-related color centers develop in quartz-bearing igneous and hydrothermal rocks, commonly in granitic pegmatites. Individual crystals may be millions to hundreds of millions of years old, depending on the host rock.

Uses & applications

Used as a gemstone, cabochon, ornamental stone, and inexpensive collector specimen; tumbling produces its smooth surface.

Geological facts

The brown color is caused by color centers associated with irradiation and trace aluminum. Similar-looking polished stones may be amethyst, chalcedony, glass, or dyed quartz.

Field identification & locations

Check glassy luster, hardness, and lack of bubbles; quartz should scratch ordinary glass but not be scratched by a steel knife. Common sources include Brazil, Madagascar, Switzerland, the United States, and Scotland.