mineral

Tumbled smoky quartz

Quartz (SiO₂), brown to gray variety colored by irradiation and trace defects

AI-generated identification · may be incorrect

Mohs hardness 7; translucent smoky-brown color, vitreous luster, conchoidal fracture, no cleavage, and trigonal crystal structure. The rounded surface indicates tumbling or polishing, with internal veils and fractures visible.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities in igneous rocks; color develops through natural radiation acting on aluminum-related defects. Quartz is widespread from Precambrian to modern geological settings.

Uses & applications

Used as a decorative and lapidary stone, carving material, and inexpensive collector specimen; occasionally set in jewelry. Typical value is about $5–$25 for a small tumbled piece, higher for exceptional clarity or color.

Geological facts

Smoky quartz is the official gemstone of Scotland and occurs in crystals ranging from tiny grains to exceptionally large specimens. Heat treatment can lighten or alter its color.

Field identification & locations

Identify it by its glassy luster, hardness, translucency, lack of cleavage, and conchoidal chips; it should scratch ordinary glass but not be scratched by a steel knife. Common sources include Brazil, Switzerland, Scotland, the United States, Madagascar, and China.