mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Gray to brown or black translucent; Luster: Vitreous; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Gray to brown or black translucent
Luster: Vitreous

Identified April 22, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Gray to brown or black translucent; Luster: Vitreous; Crystal Structure: Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

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

Uses & applications

Used primarily in jewelry (faceting and cabochons), as an ornamental stone, and in crystal healing collections. Historically used for protective eyewear (early sunglasses) in ancient China.

Geological facts

Smoky quartz is the national gem of Scotland. The dark color can vary from a faint 'smoke' to a nearly opaque black variety known as 'morion.'

Field identification & locations

Identify by its smoky translucence, hexagonal habit (if untumbled), and superior hardness (it will scratch glass). Commonly found in the Swiss Alps, Brazil, and Colorado, USA.