mineral

Quartz (Smoky Quartz)

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale, brownish-gray to dark brown color, vitreous luster, trigonal crystal system, conchoidal fracture, specific gravity of 2.65

Identified August 6, 2026More mineral →

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Physical properties

Hardness of 7 on the Mohs scale, brownish-gray to dark brown color, vitreous luster, trigonal crystal system, conchoidal fracture, specific gravity of 2.65

Formation & geological history

Forms in igneous, metamorphic, and sedimentary environments; commonly crystallizes from silica-rich hydrothermal fluids and pegmatites, often colored by natural irradiation of aluminum impurities.

Uses & applications

Used in jewelry, decorative items, oscillators in electronics, and silica glass manufacturing.

Geological facts

Smoky quartz is the national gemstone of Scotland and has been used historically for ornaments and protective amulets.

Field identification & locations

Identified by its distinct conchoidal fracture, lack of cleavage, hardness scratching glass easily, and characteristic smoky brown color. Found worldwide, particularly in Brazil, the United States, and the Swiss Alps.