mineral

Smoky quartz

Quartz, silicon dioxide (SiO₂), brown to gray variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent smoky-brown to gray, vitreous luster, conchoidal fracture, no cleavage, hexagonal crystal structure. The specimen appears rough and partly weathered, with possible iron-oxide staining or matrix.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities of igneous rocks; smoky color commonly results from natural irradiation affecting aluminum impurities. Individual crystals may range from recent geologic growth to hundreds of millions of years old.

Uses & applications

Used as a collector mineral and occasionally in jewelry; quartz is also important in glassmaking, electronics, foundry applications, and engineered stone.

Geological facts

Smoky quartz is one of the most common quartz varieties and can be naturally darkened or artificially irradiated. Its conchoidal fracture and glassy appearance distinguish it from many dark rocks.

Field identification & locations

Common localities include Brazil, Switzerland, Scotland, the United States, Madagascar, and Spain. Confirm with a hardness test against glass and inspect for conchoidal fracture; avoid scratching valuable specimens.