mineral

Smoky Quartz on Matrix

Silicon Dioxide (SiO2) with trace impurities and aluminum inclusions

Hardness: 7 on the Mohs scale. Color: Translucent grey to brownish-black (smoky) with white matrix. Luster: Vitreous (glassy). Crystal Structure: Hexagonal (trigonal) crystal system. Cleavage: None (conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Translucent grey to brownish-black (smoky) with white matrix
Luster: Vitreous (glassy)

Identified March 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the slow cooling of silica-rich hydrothermal fluids or within igneous pegmatites. The smoky color results from natural irradiation of aluminum-bearing quartz crystals over millions of years. This specimen appears to be from a granitic host rock.

Uses & applications

Commonly used as a pocket stone for collectors, in the manufacture of lapidary items (metaphysical sculptures), and sometimes as a minor gemstone for jewelry. High-purity quartz is also used in electronics for its piezoelectric properties.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm.' The dark color can be reversed through heating, which may turn the crystal clear or yellow (citrine).

Field identification & locations

Identify in the field by its distinct smoky transparency, lack of cleavage, and ability to scratch glass. It is commonly found in mountainous regions with granitic outcrops, such as the Colorado Rockies, the Swiss Alps, or Minas Gerais, Brazil.

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