mineral

Tumbled smoky quartz (probable)

Quartz, silicon dioxide (SiO₂), smoky variety colored by irradiation-related defects

AI-generated identification · may be incorrect

Typically Mohs hardness 7, vitreous luster, transparent to translucent brown-gray color, and conchoidal fracture; quartz is trigonal and lacks cleavage. The rounded, glossy surface indicates tumbling and polishing.

Identified September 7, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities in igneous rocks; coloration develops from natural irradiation of aluminum-bearing quartz over geological time. Common deposits range from Precambrian to younger host rocks.

Uses & applications

Used as an inexpensive ornamental and lapidary stone, jewelry bead, meditation stone, and mineral specimen. This piece is polished rather than naturally crystalline.

Geological facts

The photograph supports quartz but cannot rule out polished glass, obsidian, or another dark gemstone without tests. Visible internal fractures or inclusions are consistent with quartz.

Field identification & locations

Check for quartz’s hardness by testing glass cautiously, inspect for conchoidal fracture and inclusions, and use a refractometer or specific-gravity test for confirmation. Common sources include Brazil, Madagascar, Switzerland, the United States, and Spain.