mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent gray to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Translucent gray to brownish-black
Luster: Vitreous (glassy)

Identified July 19, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Translucent gray to brownish-black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Smoky quartz forms in igneous and metamorphic rocks, particularly granite pegmatites. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years within the Earth's crust.

Uses & applications

Used in jewelry, as gemstone carvings, in metaphysical practices, and occasionally in the manufacture of high-precision pressure sensors or optical components.

Geological facts

The dark color is often stable, but can fade if exposed to high heat or prolonged direct sunlight. It is the national gemstone of Scotland, where it is known as Cairngorm.

Field identification & locations

Look for the characteristic glassy luster and conchoidal (shell-like) fracture patterns. It is frequently found in riverbeds near granite mountain ranges or in vugs within pegmatite veins.