mineral

Smoky Quartz

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Brownish-gray to translucent yellow-brown; Luster: Vitreous (glassy); Crystal Structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Brownish-gray to translucent yellow-brown
Luster: Vitreous (glassy)

Identified April 4, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites and hydrothermal veins. Its color is caused by natural irradiation from surrounding minerals reacting with trace amounts of aluminum within the crystal lattice.

Uses & applications

Used in jewelry (faceted stones and beads), as ornamental carvings, and in metaphysical collecting. Historically used for making primitive eyewear in China.

Geological facts

Smoky quartz is the national gem of Scotland, where it is often referred to as 'Cairngorm' after the Cairngorm Mountains. The dark color is essentially a 'sunburn' caused by radioactivity over millions of years.

Field identification & locations

Identify by its glassy luster, lack of distinct cleavage, and ability to scratch glass easily. Look for it in granite outcroppings or as water-worn pebbles in stream beds.