mineral

Smoky Quartz with Milky Quartz

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale. Luster: Vitreous (glassy). Color: Transparent white to milky white and translucent dark brownish-grey to black. Crystal structure: Trigonal/Hexagonal. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Luster: Vitreous (glassy)

Identified July 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous, metamorphic, and hydrothermal vein environments. The dark color in smoky quartz is produced by natural ionizing radiation acting on aluminum impurities within the quartz crystal lattice during or after formation.

Uses & applications

Used in lapidary arts, jewelry, mineral specimen collections, and historically in optical instruments and oscillator crystals.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Smoky quartz gets its characteristic dark color from natural gamma radiation exposure over geological time, acting on trace amounts of aluminum substituted for silicon.

Field identification & locations

Identified by its vitreous luster, hardness 7 (scratches glass, cannot be scratched by steel), uneven conchoidal fracture, and zoned dark to milky-white coloration. Very common worldwide in pegmatites, granites, and quartz veins.