mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Pale yellowish-brown to grayish-brown; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Pale yellowish-brown to grayish-brown
Luster: Vitreous (glassy)

Identified April 3, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Pale yellowish-brown to grayish-brown; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The color is caused by natural irradiation of aluminum impurities in the quartz structure over geological time.

Uses & applications

Used in electronics for its piezoelectric properties, as gemstones in jewelry, and highly popular as metaphysical or collection specimens.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm'. The dark color can vary significantly depending on the amount of radiation exposure the crystal received while underground.

Field identification & locations

Identify in the field by its hardness (scratches glass), glass-like luster, and lack of cleavage planes. Found globally with prominent deposits in Brazil, Switzerland, and the United States (Colorado).