mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 Mohs; Color: Brownish-grey to black smoky translucence; Luster: Vitreous; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 Mohs
Color: Brownish-grey to black smoky translucence
Luster: Vitreous

Identified May 16, 2026More mineral →

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Physical properties

Hardness: 7 Mohs; Color: Brownish-grey to black smoky translucence; Luster: Vitreous; Crystal Structure: Hexagonal (Trigonal); Cleavage: None (Conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed in igneous and metamorphic rocks, primarily pegmatites and hydrothermal veins. The smoky color is caused by natural irradiation of aluminum-containing quartz over millions of years.

Uses & applications

Used extensively in jewelry as gemstones, in metaphysical practices, and as collector specimens. Occasionally used in industrial optics.

Geological facts

The dark color is often the result of free silicon formed from silicon dioxide by natural radiation. Rare, nearly opaque black varieties are known as 'Morion'.

Field identification & locations

Identified by its transparency, smoky brown hue, and hardness (scratches glass). Look for lack of cleavage and typical quartz hexagonal prism habits in raw forms. Found in Brazil, USA, and the Swiss Alps.