mineral

Smoky Quartz Cluster

Quartz (Silicon Dioxide) - SiO2

Hardness: 7 (Mohs scale); Color: Brown, black, or grey smoky hues; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Brown, black, or grey smoky hues
Luster: Vitreous (glassy)

Identified April 1, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Brown, black, or grey smoky hues; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65

Formation & geological history

Formed in pegmatites, hydrothermal veins, and igneous rocks through the natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used in gemstone carvings, jewelry, metaphysical collection, and historically in some optical components or early sunglasses in China.

Geological facts

The brown color is caused by free silicon formed from the silicon dioxide by natural irradiation. It is the national gem of Scotland, where it is often referred to as 'Cairngorm' after the mountain range.

Field identification & locations

Identify in the field by its crystal habit (six-sided prisms meeting at a point), its ability to scratch glass, and the lack of cleavage. Commonly found in granite-rich mountainous regions.

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