mineral
Smoky quartz
Quartz, SiO₂ (smoky variety)
AI-generated identification · may be incorrectTranslucent brown-gray with a vitreous luster and irregular, conchoidal fracture; Mohs hardness 7, specific gravity about 2.65, and hexagonal crystal structure. The pictured piece appears rough and fractured, with no obvious cleavage.
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Physical properties
Translucent brown-gray with a vitreous luster and irregular, conchoidal fracture; Mohs hardness 7, specific gravity about 2.65, and hexagonal crystal structure. The pictured piece appears rough and fractured, with no obvious cleavage.
Formation & geological history
Quartz crystallized from silica-rich fluids or melts in veins and pegmatites; its smoky color commonly results from natural irradiation acting on trace aluminum. Quartz occurs in rocks of many geological ages.
Uses & applications
Used in jewelry and carvings, as a collector specimen, and—like other quartz—in glassmaking and electronics.
Geological facts
Smoky quartz’s color can range from pale gray-brown to nearly black; heating or irradiation can alter its color.
Field identification & locations
Look for glassy luster, hardness sufficient to scratch glass, and conchoidal fracture rather than cleavage. Common sources include Brazil, the Alps, Scotland, and the western United States.
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Epidote
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Granite
Granite (Phaneritic intrusive igneous rock)
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