mineral

Smoky Quartz

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Grey, brown, to black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Grey, brown, to black
Luster: Vitreous

Identified April 4, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grey, brown, to black; Luster: Vitreous; Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.

Formation & geological history

Formed in igneous or metamorphic rocks like granite or gneiss. The smoky color is caused by natural irradiation of aluminum-bearing quartz over geological time.

Uses & applications

Used in jewelry (faceted stones, beads), electronics (piezoelectric properties), and widely collected by mineral enthusiasts.

Geological facts

The dark color is the result of free silicon formed from silicon dioxide by natural irradiation. If heated to about 300-400 degrees Celsius, it can lose its smoky color.

Field identification & locations

Identify in the field by its hexagonal crystal habit, lack of cleavage, and translucent 'smoke' color. Commonly found in pegmatite veins and alpine fissures globally, especially in Brazil and the USA.