mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: transluceny smoky grey-brown to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

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

Identified January 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic environments such as pegmatites or hydrothermal veins. Its distinct color is caused by natural gamma irradiation of clear quartz containing trace amounts of aluminum over millions of years.

Uses & applications

Commonly used in jewelry (beads, faceted stones), ornamental carvings, and by collectors. In industry, high-purity quartz is used in electronics and optical components.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' after the mountains where it was historically found. Its color can range from a light yellowish-grey to a 'Morion' variety which is nearly opaque black.

Field identification & locations

Identify in the field by its hardness (will scratch glass but not topaz), its lack of cleavage, and its smoky transparency. Common locations include Brazil, Madagascar, the Swiss Alps, and the Pikes Peak region of Colorado, USA.