mineral
Polished smoky quartz pendant
Smoky quartz, silicon dioxide (SiO₂), colored by irradiation-related defects
AI-generated identification · may be incorrectTranslucent gray-brown to nearly black, with vitreous luster and no visible cleavage; Mohs hardness 7, trigonal crystal structure, and specific gravity about 2.65. The specimen is polished and wire-wrapped, so its natural crystal form is obscured.
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Physical properties
Translucent gray-brown to nearly black, with vitreous luster and no visible cleavage; Mohs hardness 7, trigonal crystal structure, and specific gravity about 2.65. The specimen is polished and wire-wrapped, so its natural crystal form is obscured.
Formation & geological history
Forms in hydrothermal veins, granitic pegmatites, and cavities in igneous rocks when trace aluminum defects in quartz are exposed to natural radiation. It may range from Precambrian to recent in age, depending on the host rock.
Uses & applications
Commonly used for cabochons, pendants, beads, and ornamental objects; quartz is also important industrially in glass, electronics, and foundry materials.
Geological facts
Smoky coloration can fade with strong heating or sunlight, while very dark material may be called morion. The brown tone is generally natural rather than a surface coating.
Field identification & locations
Identify it by its glassy luster, hardness, conchoidal fracture, and lack of cleavage; it should scratch ordinary glass but not be scratched by a steel knife. Major sources include Brazil, Switzerland, the United States, Madagascar, and Scotland.
