mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent to opaque smoky brown or grey; Luster: Vitreous (glass-like); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Translucent to opaque smoky brown or grey
Luster: Vitreous (glass-like)

Identified June 16, 2026More mineral →

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Physical properties

Formation & geological history

Smoky quartz forms in igneous rocks like granite and pegmatites. Its distinctive color is caused by natural irradiation of trace aluminum impurities within the silicon dioxide crystal lattice during its formation.

Uses & applications

Widely used for fashion jewelry, ornamental carvings, crystal healing collections, and as an abrasive in industrial applications.

Geological facts

The smoky color can be artificially produced by irradiating clear quartz, but natural specimens owe their tint to millions of years of exposure to background radiation from surrounding rock. Scotland considers yellow-brown smoky quartz, known as 'Cairngorm', as its national gemstone.

Field identification & locations

Identify in the field by its distinct smoky transparency, hexagonal crystal habit, and its ability to scratch glass. Found globally, with notable deposits in Brazil, Switzerland, and the United States (notably Colorado).