mineral
Smoky Quartz
Silicon Dioxide (SiO2)
Hardness: 7 (Mohs scale), Color: Brownish-grey to black, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
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Physical properties
Hardness: 7 (Mohs scale), Color: Brownish-grey to black, Luster: Vitreous (glassy), Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific Gravity: 2.65
Formation & geological history
Formed in igneous or metamorphic rocks through the natural irradiation of aluminum-bearing quartz crystals over millions of years. Commonly found in pegmatite veins.
Uses & applications
Used primarily in gemstones, ornamental carvings, and by crystal collectors. Historically used for one of the earliest forms of sunglasses in China.
Geological facts
The dark color is caused by free silicon formed from silicon dioxide by natural irradiation. Cairngorm is a famous variety found in the Scottish Highlands.
Field identification & locations
Identify by its smoky transparency, hardness (scratches glass), and lack of cleavage. Found globally in granitic mountains and hydrothermal veins.
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Arenite (SiO2 based)
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Nephrite Jade
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Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
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Green Apatite on Albite
Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]
mineral
Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
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