mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: Brown to black smoky translucent color, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified May 16, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Brown to black smoky translucent color, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Forms in igneous and metamorphic rocks, specifically in pegmatites and hydrothermal veins. The smoky color is caused by natural radiation from surrounding rock acting on trace amounts of aluminum within the quartz structure.

Uses & applications

Used extensively in jewelry for faceted gemstones, beads, and carvings. Also popular as a healing crystal in metaphysical circles and as ornamental display specimens for collectors.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' after the mountain range where it is traditionally found. It is one of the few brown gemstones used in jewelry.

Field identification & locations

Identify in the field by its hardness (will scratch glass), translucent brown color without regular cleavage planes, and conchoidal (shell-like) fractures. Found worldwide, with major deposits in Brazil, Switzerland, and the USA.