mineral

Smoky Quartz

Smoky Quartz (SiO2: Silicon Dioxide)

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

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

Identified March 25, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in igneous or metamorphic environments, primarily pegmatites. The smoky color is caused by natural radiation from surrounding rocks acting on trace amounts of aluminum within the crystal lattice during formation, often millions of years ago.

Uses & applications

Used in gemstone jewelry (faceting and cabochons), crystal healing/collecting, and historically for early sunglasses in China. 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 known as Cairngorm. Very dark, opaque varieties are called 'Morion'. The color can often be changed to yellow (citrine-like) by heat treatment.

Field identification & locations

Identify in the field by its distinct conchoidal (shell-like) fracture, hardness (it will scratch glass), and translucent smoky color. Common in mountainous regions like the Alps, Brazil, and Colorado, USA. Look for it in granite outcroppings.