mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent to opaque, varying from yellowish-brown to deep black; Luster: Vitreous (glass-like); Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous (glass-like)

Identified March 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous or metamorphic rocks, such as granite or gneiss. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years. It is found in hydrothermal veins and pegmatite pockets.

Uses & applications

Used primarily in jewelry as a gemstone, in spiritual practices/meditation, and as collector specimens. Historically used for making early pince-nez style sunglasses in 12th century China.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' because it was famously mined in the Cairngorm Mountains. Very dark, opaque varieties are specifically called 'morion'.

Field identification & locations

Identify in the field by its hardness (will scratch glass), translucent brown-to-charcoal color, and lack of cleavage. Common in mountainous regions like the Alps, Brazil, and Colorado. Look for hexagonal points in geode pockets.