mineral

Smoky Quartz (with possible Garnet inclusions)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Brownish-grey, chocolate brown to black; Luster: Vitreous (glassy); Crystal structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

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

Identified March 30, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Brownish-grey, chocolate brown to black; Luster: Vitreous (glassy); Crystal structure: Hexagonal; Cleavage: None/Conchoidal fracture; Specific gravity: 2.65

Formation & geological history

Formed in high-temperature environments, typically in igneous rocks like pegmatites or metamorphic rocks. Often colored by natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used widely in lapidary work, jewelry, and as decorative metaphysical specimens. Higher quality clear crystals are used in precision instruments.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm'. The dark color is caused by trace amounts of aluminum and exposure to natural gamma radiation from the surrounding rock.

Field identification & locations

Identify in the field by its hexagonal crystal habit, lack of cleavage, and 'smoky' translucency. Commonly found in Brazil, Switzerland, and the USA (Colorado). Collectors look for well-defined crystal faces and deep, uniform color.

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