mineral

Smoky Quartz

Smoky Quartz (Silicon Dioxide, SiO2)

Hardness: 7 (Mohs scale), Color: Translucent brownish-grey to smoky yellow, Luster: Vitreous (glassy), Crystal system: Hexagonal/Trigonal, Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Identified April 4, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale), Color: Translucent brownish-grey to smoky yellow, Luster: Vitreous (glassy), Crystal system: Hexagonal/Trigonal, Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Formation & geological history

Forms in igneous and metamorphic rocks, particularly pegmatites and hydrothermally vein deposits. The color results from natural irradiation of aluminum-bearing quartz over millions of years.

Uses & applications

Used in jewelry (faceting), gemstone carvings, ornamental decor, and as healing crystals in metaphysical practices. Historically used for making the first sunglasses in 12th century China.

Geological facts

Smoky quartz is the national gem of Scotland, where it is often referred to as 'Cairngorm'. Its dark color can be synthetically enhanced or lightened through heat treatment.

Field identification & locations

Identify by its glassy luster, smoky translucency, and ability to scratch glass (hardness 7). It lacks cleavage, breaking like glass into curved surfaces. Commonly found in granitic terrains.