mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Brownish-grey, translucent; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Brownish-grey, translucent
Luster: Vitreous (glassy)

Identified March 11, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Brownish-grey, translucent; Luster: Vitreous (glassy); Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in igneous environments (granitic pegmatites) or hydrothermal veins. The smoky color is caused by natural irradiation of free silicon within the quartz crystal over millions of years.

Uses & applications

Used in jewelry (gems), metaphysical collecting, and historically for early sunglasses in 12th century China. High-purity quartz is also vital for electronics and glassmaking.

Geological facts

The dark color is often the result of aluminum impurities that were exposed to radiation from surrounding rocks. Brazil is currently the world's largest supplier of commercial smoky quartz.

Field identification & locations

Identify by its hardness (will scratch glass), translucent grey/brown color, and lack of cleavage. Commonly found in mountainous regions with granitic bedrock. Beginners should look for its glassy luster and resistance to weathering.