mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent grey to brownish-black; Luster: Vitreous; Crystal System: Trigonal (Hexagonal prisms); Cleavage: None/Conchoidal fracture; SG: 2.65

Hardness: 7 on Mohs scale
Color: Translucent grey to brownish-black
Luster: Vitreous

Identified June 7, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Translucent grey to brownish-black; Luster: Vitreous; Crystal System: Trigonal (Hexagonal prisms); Cleavage: None/Conchoidal fracture; SG: 2.65

Formation & geological history

Formed in igneous or metamorphic rocks, specifically pegmatites, through the natural irradiation of aluminum-bearing quartz over geological time. Often found in pockets and alpine clefts.

Uses & applications

Used primarily as a gemstone for jewelry (rings, pendants), as a healing crystal in metaphysical practices, and as a popular mineral specimen for collectors.

Geological facts

The dark color is caused by free silicon formed from silicon dioxide by natural irradiation. Cairns in Scotland are famous for a specific dark variety known as 'Cairngorm'.

Field identification & locations

Identify by its smoky translucence and hardness (it will scratch glass). Commonly found in the Swiss Alps, Brazil, Madagascar, and the United States (Colorado).