mineral

Smoky quartz crystal fragment

Quartz, silicon dioxide (SiO₂), likely smoky variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; translucent gray-brown to smoky black, with vitreous luster and conchoidal fracture. Hexagonal crystal structure; distinct cleavage is absent, though the specimen appears naturally fractured or partly crystal-faced.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Smoky quartz forms when natural irradiation activates aluminum impurities in quartz, commonly in granite pegmatites, hydrothermal veins, and metamorphic cavities. Its exact geological age cannot be determined from the photograph and may range from relatively young to Precambrian.

Uses & applications

Used as a collectible mineral and occasionally as a gemstone; quartz is also important industrially in glass, electronics, abrasives, and ceramics. This small irregular fragment has modest specimen value.

Geological facts

The smoky color is generally caused by color centers involving trace aluminum rather than a separate mineral. Heating can remove the smoky color, while prolonged radiation exposure can sometimes intensify it.

Field identification & locations

Identify it by its glassy luster, gray-brown transparency, hardness sufficient to scratch ordinary glass, and lack of cleavage; confirm with a hardness and specific-gravity test. Common localities include Brazil, Switzerland, the United States, Madagascar, and Scotland.