mineral
Smoky quartz crystal
Quartz, silicon dioxide (SiO₂), likely smoky variety
AI-generated identification · may be incorrectTranslucent gray-brown to nearly black, with vitreous luster and conchoidal fracture; Mohs hardness 7, hexagonal crystal structure, no true cleavage, and specific gravity about 2.65. The specimen appears raw and fractured, with possible iron- or radiation-induced smoky coloration.
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Physical properties
Translucent gray-brown to nearly black, with vitreous luster and conchoidal fracture; Mohs hardness 7, hexagonal crystal structure, no true cleavage, and specific gravity about 2.65. The specimen appears raw and fractured, with possible iron- or radiation-induced smoky coloration.
Formation & geological history
Forms in silica-rich hydrothermal veins, pegmatites, and cavities in igneous rocks; smoky color develops through natural irradiation of aluminum-bearing quartz. Individual crystals range from recent growth to hundreds of millions of years old, depending on the host deposit.
Uses & applications
Used as a collectible mineral and occasionally as a gemstone when transparent and well-formed; quartz is also essential in glass, electronics, abrasives, and engineered stone.
Geological facts
Smoky quartz can grade from pale gray (“cairngorm”) to opaque morion. Its color may fade with strong heating or prolonged sunlight, and some commercial dark material is artificially irradiated.
Field identification & locations
Identify it by hardness, glassy luster, conchoidal fracture, and lack of cleavage; it should scratch ordinary glass but not be scratched by a steel knife. Common sources include Brazil, Switzerland, Scotland, Colorado, Arkansas, and Madagascar.
