mineral

Quartz (Smoky Quartz)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Grayish-brown to smoky black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture.

Hardness: 7 on Mohs scale
Color: Grayish-brown to smoky black
Luster: Vitreous (glassy)

Identified July 20, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grayish-brown to smoky black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture.

Formation & geological history

Forms in igneous rocks like granite or in hydrothermal veins. The smoky color is caused by natural irradiation of aluminum-bearing quartz over long geological periods.

Uses & applications

Used in electronics for quartz oscillators, as an abrasive, and popular in jewelry or as metaphysical healing crystals.

Geological facts

Smoky quartz is the national gem of Scotland, where it is often referred to as 'Cairngorm' after the mountains where it is mined.

Field identification & locations

Identify by its ability to scratch glass, lack of cleavage (breaks like glass), and smoky transparency. Commonly found in mountainous regions with granitic bedrock.