mineral

Tumbled smoky quartz

Quartz, silicon dioxide (SiO₂), smoky variety

AI-generated identification · may be incorrect

Typically translucent gray-brown to smoky black with a vitreous luster; Mohs hardness 7, conchoidal fracture, no cleavage, and hexagonal crystal structure. The rounded surface indicates human tumbling or polishing.

Identified August 25, 2026More mineral →

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Physical properties

Formation & geological history

Smoky quartz forms when natural or irradiation-induced color centers develop in quartz-bearing igneous and metamorphic rocks, commonly in granite and pegmatite cavities. The specimen’s exact age and locality cannot be determined from the image.

Uses & applications

Used as a decorative and lapidary stone, in carvings, cabochons, and inexpensive jewelry; it has limited industrial value compared with ordinary quartz.

Geological facts

Smoky coloration is commonly caused by aluminum impurities activated by natural radiation. Heating can remove or alter the color, sometimes producing citrine-like tones.

Field identification & locations

Identify it by its smoky translucency, glassy luster, hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Switzerland, Madagascar, the United States, and Scotland.