mineral

Tumbled smoky quartz

Quartz, silicon dioxide (SiO₂), colored by irradiation and trace aluminum

AI-generated identification · may be incorrect

Mohs hardness 7; translucent smoky-brown to gray, with vitreous luster and conchoidal fracture. It is a tumbled, rounded specimen, so natural crystal faces and cleavage are absent; quartz has a trigonal crystal structure and no cleavage.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, cavities, and pegmatites when natural radiation produces the smoky color; crystals range from Precambrian to recent. The rounded surface indicates human tumbling and polishing.

Uses & applications

Used as a collectible and ornamental stone, in cabochons and jewelry, and occasionally for carvings; quartz is also important industrially in glass, electronics, and abrasives.

Geological facts

Smoky quartz is the national gemstone of Scotland and is commonly associated with feldspar, mica, and other pegmatite minerals.

Field identification & locations

Identify it by its brown-gray transparency, glassy luster, hardness, and lack of cleavage; common sources include Brazil, Switzerland, Scotland, Madagascar, and the United States. White patches may be quartz, feldspar, or surface abrasion, and confirmation requires hardness or gemological testing.