mineral

Smoky Quartz (Tumbled)

Smoky Quartz (Silicon Dioxide - SiO2)

Hardness: 7 Mohs scale. Color: Translucent grey to brownish-black. Luster: Vitreous (glass-like). Crystal structure: Trigonal/Hexagonal. Cleavage: None (Conchoidal fracture). Specific Gravity: 2.65.

Hardness: 7 Mohs scale
Color: Translucent grey to brownish-black
Luster: Vitreous (glass-like)

Identified March 25, 2026More mineral →

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Physical properties

Hardness: 7 Mohs scale. Color: Translucent grey to brownish-black. Luster: Vitreous (glass-like). Crystal structure: Trigonal/Hexagonal. Cleavage: None (Conchoidal fracture). Specific Gravity: 2.65.

Formation & geological history

Formed in igneous and metamorphic rocks, particularly pegmatites. The smoky color is caused by natural irradiation of aluminum-bearing quartz over geological time (often millions of years).

Uses & applications

Commonly used in jewelry (rings, pendants), decorative carvings, and as a popular 'grounding' stone in metaphysical practices. Industrially, quartz is used in electronics and glass-making.

Geological facts

Smoky quartz is the national gem of Scotland, where it is known as 'Cairngorm.' The dark color is and can be reversed by heating the stone to several hundred degrees.

Field identification & locations

Identify by its translucent brownish-grey color and ability to scratch glass but not topaz. Commonly found in Brazil, Madagascar, and the USA (Colorado and New Hampshire). For collectors, look for clarity and depth of color.

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