
mineral
Tumbled smoky quartz
Quartz (SiO₂), likely smoky variety
AI-generated identification · may be incorrectHardness 7 Mohs; translucent brown to gray-brown with a vitreous polish, no visible cleavage, and hexagonal crystal structure (obscured by tumbling). Specific gravity is about 2.65.
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Physical properties
Hardness 7 Mohs; translucent brown to gray-brown with a vitreous polish, no visible cleavage, and hexagonal crystal structure (obscured by tumbling). Specific gravity is about 2.65.
Formation & geological history
Forms in silica-rich hydrothermal veins, pegmatites, and cavities of igneous rocks; smoky coloration commonly results from natural irradiation affecting aluminum impurities. The specimen is human-polished and its precise geological age cannot be determined.
Uses & applications
Used as an ornamental and lapidary stone, in jewelry, carvings, and mineral collections; common tumbled pieces have modest commercial value.
Geological facts
Smoky quartz ranges from pale gray to nearly black (“morion”); heating can remove the color, while irradiation can produce it in otherwise clear quartz.
Field identification & locations
Identify by its glassy luster, hardness, translucency, conchoidal fracture, and resistance to scratching by steel; unlike brown glass, it feels cool and will scratch ordinary window glass. Common sources include Brazil, Switzerland, Madagascar, and the United States.
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Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous