mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Brownish gray to near-black; Luster: Vitreous; Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Brownish gray to near-black
Luster: Vitreous

Identified June 21, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Brownish gray to near-black; Luster: Vitreous; Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Forms in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins, where natural radiation from surrounding rocks colors clear quartz over millions of years.

Uses & applications

Used in jewelry (gemstones), metaphysical collecting, and historically in the first-ever sunglasses in 12th century China.

Geological facts

The dark color is caused by free silicon formed from silicon dioxide by natural irradiation. Cairns in Scotland often use 'Cairngorm' smoky quartz as a traditional ornament.

Field identification & locations

Identify by its transparency, conchoidal fracture, and lack of cleavage. Often found in mountainous regions like the Alps, Brazil, and the Pikes Peak area of Colorado.