mineral
Smoky Quartz
Silicon Dioxide (SiO2) with aluminum impurities
Hardness: 7 (Mohs scale), Color: Brown to blackish-gray, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: Indistinct/Conchoidal fracture, Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Brown to blackish-gray, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: Indistinct/Conchoidal fracture, Specific Gravity: 2.65
Formation & geological history
Formed in igneous or metamorphic rocks, particularly pegmatites and hydrothermal veins. The smoky color is caused by natural irradiation of aluminum-bearing quartz over millions of years.
Uses & applications
Used primarily in jewelry (gemstone), metaphysical collecting, and historically for early sunglasses in 12th century China.
Geological facts
The color is not stable at very high temperatures and can fade if subjected to intense sunlight or heat; it is the national gem of Scotland, where it is often called Cairngorm.
Field identification & locations
Identify by its characteristic transparency paired with a brown/smoke tint and its ability to scratch glass. Commonly found in Brazil, Madagascar, and the Swiss Alps.
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