mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Gray to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Gray to brownish-black
Luster: Vitreous (glassy)

Identified June 19, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Gray to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed in igneous and metamorphic rocks, especially pegmatites and hydrothermal veins. The smoky color is caused by natural radiation from surrounding rocks acting on aluminum impurities within the quartz crystal structure.

Uses & applications

Used extensively in jewelry, metaphysical collections, and as a component in glassmaking or precision electronics if of high purity.

Geological facts

Unlike many colored minerals, smoky quartz gets its hue through radiation-induced center defects. It is the national gemstone of Scotland, where it is known as Cairngorm.

Field identification & locations

Identify by its glass-like luster, hardness (can scratch glass), and lack of cleavage. Common in crystalline regions like the Alps, Brazil, and the Rocky Mountains.