mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale), Color: Brownish grey to black, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified April 11, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Brownish grey to black, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Formation & geological history

Forms in igneous rocks like granite or metamorphic rocks like gneiss. The smoky color is caused by natural irradiation from radioactive minerals in surrounding rock, which activates aluminum impurities within the crystal lattice.

Uses & applications

Used primarily as gemstones in jewelry, for decorative carvings, as collectibles, and in metaphysical practices. High-quality piezoelectric quartz is used in electronics, though synthetic quartz is now more common for industrial use.

Geological facts

Smoky quartz is the national gem of Scotland, where it was traditionally known as Cairngorm. Deeply colored, almost opaque specimens are called Morion.

Field identification & locations

Identify by its glass-like appearance, lack of cleavage, and the characteristic conchoidal (shell-like) fracture. Look for it in pegmatite veins or as crystals in vugs within granite outcrops.