mineral

Smoky Quartz on Matrix

Crystalline Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Grey, brownish-black, to translucent white; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (Trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Grey, brownish-black, to translucent white
Luster: Vitreous (glassy)

Identified June 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous or metamorphic environments, specifically in pegmatites or hydrothermal veins where silicon-rich fluids crystallize over long periods. The smoky color is often caused by natural radiation from surrounding rocks acting on aluminum impurities.

Uses & applications

Used as a gemstone in jewelry, as a healing crystal in metaphysical practices, and as decorative cabinet specimens for collectors. In industry, high-purity quartz is used in electronics and glass-making.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm' after the mountain range where it was historically found. It is one of the few grey-to-brown colored gemstones.

Field identification & locations

Identify in the field by its distinct hexagonal crystal points, inability to be scratched by a steel knife (H=7), and glassy luster. Commonly found in granite-rich regions like the Alps, Brazil, and the Southwestern United States.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic