mineral
Tumbled smoky quartz
Quartz, silicon dioxide (SiO₂), smoky variety colored by irradiation-related defects
AI-generated identification · may be incorrectMohs hardness 7; translucent gray-brown to smoky black, vitreous luster, commonly massive rather than visibly crystalline, with indistinct cleavage and conchoidal fracture; specific gravity about 2.65.
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Physical properties
Mohs hardness 7; translucent gray-brown to smoky black, vitreous luster, commonly massive rather than visibly crystalline, with indistinct cleavage and conchoidal fracture; specific gravity about 2.65.
Formation & geological history
Forms in silica-rich hydrothermal veins, pegmatites, and cavities of igneous rocks, where natural radiation creates its smoky color. Individual specimens may range from Paleozoic to recent geologic ages.
Uses & applications
Used as an ornamental and lapidary stone, for tumbled stones, carvings, jewelry, and mineral collections; it has little industrial value compared with ordinary quartz.
Geological facts
The rounded shape and glossy surface indicate mechanical tumbling and polishing. Color can fade with strong heat or sunlight, and very dark material may be artificially irradiated.
Field identification & locations
Identify it by hardness, glassy luster, translucent smoky coloration, and lack of obvious cleavage; it should scratch window glass but not be scratched by a steel knife. Common sources include Brazil, Madagascar, Switzerland, the United States, and Spain.
