mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: Smoky grey to brownish-black, Luster: Vitreous, Crystal Structure: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified May 19, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Smoky grey to brownish-black, Luster: Vitreous, Crystal Structure: Hexagonal (trigonal), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed in igneous or metamorphic rocks, particularly pegmatites and hydrothermal veins. The smoky color is caused by natural irradiation of aluminum impurities within the crystal lattice.

Uses & applications

Used in gemstone jewelry, ornamental carvings, and historical optical lenses. It is also highly popular as a collector's mineral and in metaphysical circles.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm.' Some specimens can be nearly black, a variety referred to as 'Morion.'

Field identification & locations

Identify by its characteristic greyish color, high hardness (can scratch glass), and lack of cleavage. Commonly found in riverbeds as rounded pebbles or in alpine environments high in mountain ranges.