mineral

Smoky Quartz

Quartz (SiO2) with natural radiation

Hardness: 7 on Mohs scale; Color: Translucent to opaque smokey brown, grey, or black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Translucent to opaque smokey brown, grey, or black
Luster: Vitreous

Identified June 28, 2026More mineral →

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Physical properties

Formation & geological history

Smoky quartz forms through the natural irradiation of aluminum-bearing quartz over millions of years, often in pegmatites or hydrothermal veins. Its dark color is caused by free silicon atoms formed from the silicon dioxide by natural radiation.

Uses & applications

Extensively used in jewelry (faceting and cabochons), ornamental carvings, and by collectors. In industry, high-purity quartz is used in electronics and glass-making.

Geological facts

The dark brown to black varieties are often called 'Cairngorm' in Scotland or 'Morion' if they are very dark and opaque. It is the national gem of Scotland and has been used for centuries in traditional Scottish jewelry.

Field identification & locations

Identify in the field by its hexagonal crystal habit, lack of cleavage, and characteristic translucent 'smoke' color. Commonly found in Brazil, Switzerland, and the United States (specifically Colorado and New Hampshire). Collectors should look for undamaged crystal terminations and internal clarity.