mineral

Polished brown quartz crystal (likely smoky quartz)

Quartz, silicon dioxide (SiO₂); probable smoky variety

AI-generated identification · may be incorrect

Hardness 7 Mohs; transparent to translucent brown, with vitreous luster and a hexagonal prismatic crystal form terminated by faceted/polished points. Quartz has no true cleavage, conchoidal fracture, and specific gravity about 2.65.

Identified September 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities in igneous rocks; smoky coloration commonly results from irradiation and trace aluminum. The specimen’s geological age cannot be determined from the photograph.

Uses & applications

Used as a decorative and lapidary specimen, crystal point, and sometimes jewelry; common pieces generally have modest value.

Geological facts

Its shape may be natural quartz with polished faces or a fully cut/tumbled crystal, so natural crystal habits cannot be confirmed visually alone.

Field identification & locations

Identify by its glassy luster, pointed hexagonal form, hardness, and lack of cleavage; confirm with a scratch test only on an inconspicuous area. Common sources include Brazil, Madagascar, the United States, and the Alps.