mineral

Smoky Quartz

Silicon Dioxide (SiO2) with aluminum impurities and natural radiation

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Grayish-brown to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Grayish-brown to black
Luster: Vitreous (glassy)

Identified April 27, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Grayish-brown to black; Luster: Vitreous (glassy); Crystal Structure: Hexagonal/Trigonal; 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 trace aluminum impurities which are activated by natural gamma radiation from surrounding rocks during slow crystallization over millions of years.

Uses & applications

Used widely in jewelry (rings, pendants), as ornamental display pieces in home decor, and in industrial optics/electronics (though usually synthetic quartz is preferred for precision tech).

Geological facts

Naturally occurring radiation creates the color, but the stones are safe to handle. Darker, opaque versions are often referred to as 'Morion'. Exposure to long periods of sunlight can sometimes fade the color back to clear quartz.

Field identification & locations

Identify in the field by its glassy luster, smoky transparency, and lack of cleavage (it breaks like glass). Commonly found in mountainous regions like the Alps, Brazil, and the Rocky Mountains (Pikes Peak, Colorado).