mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Grayish-brown to black translucent; Luster: Vitreous; Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Grayish-brown to black translucent
Luster: Vitreous

Identified May 11, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grayish-brown to black translucent; Luster: Vitreous; Crystal structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed in igneous or metamorphic rocks, specifically pegmatites or hydrothermal veins. The smoky color is caused by natural irradiation of trace aluminum impurities within the crystal lattice.

Uses & applications

Used in jewelry (faceted or cabochon), as ornamental stones, and in metaphysical collecting. Historically used for making early sunglasses in China.

Geological facts

Smoky quartz is the national gem of Scotland. The dark color can be deepened through artificial irradiation or lightened by heating carefully to 200-300 degrees Celsius.

Field identification & locations

Identify by its smoky gray/brown color and glassy conchoidal fractures. It will scratch glass easily. Commonly found in mountainous regions like the Alps, Brazil, and the United States (Colorado).