gemstone

Smoky quartz cabochon/faceted stone

Quartz (silicon dioxide, SiO₂), smoky variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; transparent to translucent brown-gray to nearly black, with vitreous luster and conchoidal fracture. Quartz is trigonal and lacks cleavage; the pictured stone is cut and polished, obscuring natural crystal form.

Identified August 28, 2026More gemstone →

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Physical properties

Formation & geological history

Smoky color results from irradiation affecting aluminum impurities in quartz, typically in granite-related pegmatites, hydrothermal veins, and cavities. Crystals formed during igneous cooling or later hydrothermal activity, commonly from Paleozoic to younger deposits.

Uses & applications

Used as an ornamental gemstone in jewelry, carvings, and collector specimens; durable enough for rings and pendants, though inclusions and cutting quality determine value.

Geological facts

The dark variety is sometimes called morion; heating can fade or alter the color. Color intensity may be natural or enhanced by irradiation.

Field identification & locations

Identify by glassy luster, hardness, conchoidal fracture, and brown smoke-like transparency; it should scratch ordinary glass but not be scratched by a steel knife. Common sources include Brazil, Switzerland, Madagascar, Spain, and the United States.