mineral

Smoky Quartz

Silicon Dioxide (SiO₂)

Hardness: 7 (Mohs scale), Color: Brownish-grey to black, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified April 19, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Brownish-grey to black, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. The smoky color is caused by natural irradiation of trace aluminum impurities within the quartz.

Uses & applications

Popular in jewelry (faceted or cabochon), ornamental carvings, and widely collected as mineral specimens. In industry, quartz is used for its piezoelectric properties and in glass making.

Geological facts

Smoky quartz is the national gem of Scotland, where it is often called Cairngorm. Its color can range from a light 'tea' brown to a nearly opaque 'Morion' black.

Field identification & locations

Identify by its glassy luster, lack of cleavage, and the presence of internal fractures or inclusions. Commonly found in Brazil, USA (Colorado), Switzerland, and Madagascar.