mineral

Tumbled smoky quartz (probable)

Quartz, silicon dioxide (SiO₂), smoky variety

AI-generated identification · may be incorrect

Usually translucent to opaque brown, gray-brown, or nearly black with a vitreous luster; hardness 7 Mohs, no cleavage, conchoidal fracture, and hexagonal crystal structure. The specimen is polished/tumbled, obscuring natural crystal faces.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Smoky quartz forms when natural radiation creates color centers in quartz-bearing igneous, hydrothermal, or metamorphic rocks; its age depends on the host rock, commonly hundreds of millions to billions of years. Common sources include Brazil, Madagascar, Switzerland, the United States, and Scotland.

Uses & applications

Used as an ornamental and lapidary stone, in carvings, cabochons, jewelry, and mineral collections; quartz is also important industrially in glass, electronics, and abrasives.

Geological facts

The dark color can range from pale smoky gray to morion-black and may fade with prolonged heating or strong light. Visual identification is tentative because black obsidian, tourmalinated quartz, and other dark polished stones can look similar.

Field identification & locations

Look for glassy luster, hardness sufficient to scratch ordinary glass, conchoidal fracture, and lack of cleavage; a scratch test or loupe examination can help distinguish it from obsidian. The background crystals appear to include amethyst and other tumbled minerals.