mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale, brown to black color due to natural irradiation of aluminum impurities, vitreous luster, hexagonal crystal system, conchoidal fracture with no true cleavage, specific gravity of 2.65.

Identified July 28, 2026More mineral →

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Physical properties

Formation & geological history

Formed in hydrothermal veins, pegmatites, and igneous rocks through the cooling of silica-rich fluids under high pressure and temperature over millions of years.

Uses & applications

Used in gemstone and jewelry creation, metaphysical and healing practices, and as mineral specimens for collectors.

Geological facts

Smoky quartz is the national gemstone of Scotland, where it is often known as cairngorm. The dark color is caused when natural radiation emitted from surrounding rocks activates aluminum impurities substituted for silicon in the crystal lattice.

Field identification & locations

Easily identified by its distinct brown-to-black translucent color, hexagonal prismatic crystal habit, and high hardness which scratches glass. Commonly sourced from Brazil, the US (Colorado), Switzerland, and Madagascar.