mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Brownish-grey to black
Luster: Vitreous (glassy)

Identified March 10, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Brownish-grey to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.65

Formation & geological history

Formed through the natural irradiation of aluminum-bearing rock crystal within granite pegmatites and hydrothermal veins. They can range in age from millions to billions of years old depending on the host rock formation.

Uses & applications

Used in gemstone jewelry, ornamental carvings, and electronics (historic piezoelectric applications). It is highly popular as a collector's mineral and in metaphysical circles.

Geological facts

The dark color is caused by natural radiation from surrounding rocks that activates aluminum impurities within the crystal lattice. One of the most famous varieties is 'Cairngorm' from the Scottish mountains.

Field identification & locations

Identify in the field by its hardness (will scratch glass), glassy luster, and the presence of conchoidal (shell-like) fractures rather than flat cleavage planes. Found worldwide, with major deposits in Brazil, Switzerland, and the USA (Colorado).