mineral

Tumbled smoky quartz

Quartz (silicon dioxide, SiO₂), smoky variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent gray-brown color, vitreous luster, and hexagonal crystal structure (obscured by tumbling). Quartz has no true cleavage, conchoidal fracture, and specific gravity around 2.65.

Identified September 8, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich igneous and hydrothermal veins; smoky coloration generally results from natural irradiation affecting aluminum impurities. Quartz is abundant throughout geological time, including modern and ancient deposits.

Uses & applications

Used as a collectible or ornamental tumbled stone; quartz is also important in glass, ceramics, electronics, abrasives, and construction aggregate.

Geological facts

The gray-brown color can fade with prolonged strong sunlight or heat. The pictured stone may also be gray chalcedony or another quartz variety, since a photograph cannot confirm internal texture.

Field identification & locations

Identify quartz by its glassy luster, conchoidal fracture, lack of cleavage, and ability to scratch ordinary glass; smoky quartz is commonly found in granitic pegmatites. Major sources include Brazil, Madagascar, Switzerland, and the United States.