mineral

Smoky quartz (rough, water-worn crystal)

Quartz, silicon dioxide (SiO₂), smoky variety

AI-generated identification · may be incorrect

Translucent gray-brown to smoky purple, vitreous luster, commonly massive or imperfectly crystalline; Mohs hardness 7, no cleavage, conchoidal fracture, specific gravity about 2.65. The irregular faces and transparency are consistent with a naturally fractured or tumbled quartz specimen.

Identified August 8, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities of igneous rocks; smoky coloration typically results from natural irradiation affecting trace aluminum. Quartz formed throughout geologic time, commonly from Paleozoic to modern mineral deposits.

Uses & applications

Used as a collector mineral and occasionally in cabochons or ornamental objects; clear, well-formed smoky quartz crystals are used in jewelry. Ordinary water-worn pieces have little commercial value.

Geological facts

Quartz is one of Earth’s most abundant minerals and is chemically resistant, allowing it to survive transport in streams. Brown coloration can overlap with iron-stained clear quartz or pale amethyst.

Field identification & locations

Likely identification: glassy luster, hardness sufficient to scratch ordinary glass, conchoidal fracture, and lack of cleavage; avoid confusing it with brown glass or slag. Common localities include Brazil, Madagascar, Switzerland, Colorado, and stream gravels worldwide.