mineral

Smoky quartz crystal cluster

Quartz, silicon dioxide (SiO₂), likely smoky variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent gray-brown to nearly black color, vitreous luster, hexagonal crystal structure, and indistinct cleavage with conchoidal fracture. The pictured specimen appears to contain intergrown, sharply terminated crystals, though lighting and surface coating obscure details.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Smoky quartz forms when natural irradiation activates aluminum impurities in quartz, commonly in granite pegmatites, hydrothermal veins, and cavities. Individual crystals may form over millions of years, usually in Precambrian to younger igneous settings.

Uses & applications

Used as a collector mineral, ornamental stone, and occasionally in jewelry; quartz is also important in glass, electronics, abrasives, and engineered stone.

Geological facts

The smoky color is generally caused by irradiation-induced color centers rather than inclusions. Heating can fade the smoky color or transform some material toward citrine-like yellow tones.

Field identification & locations

Common localities include Brazil, Switzerland, Scotland, Colorado, Arkansas, Madagascar, and Namibia. Identify it by glassy luster, hardness sufficient to scratch ordinary glass, hexagonal terminations, and lack of strong cleavage.