mineral

Polished smoky quartz pebble (probable)

Smoky quartz, silicon dioxide (SiO₂), colored by irradiation-related defects

AI-generated identification · may be incorrect

Translucent dark brown-gray with a vitreous luster and rounded, polished surface; quartz is Mohs hardness 7, trigonal, with indistinct cleavage and conchoidal fracture. The image cannot confirm internal crystal features or authenticity.

Identified September 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms in silica-rich hydrothermal veins, pegmatites, and cavities of igneous rocks; specimens range from geologically ancient to relatively young, depending on the host deposit. Natural color develops through irradiation of trace aluminum impurities.

Uses & applications

Used as a lapidary stone, carving material, and collectible; faceted smoky quartz is occasionally used in jewelry. Common polished pebbles typically have modest commercial value.

Geological facts

The dark color may fade with prolonged heating or intense light. A glass or dyed stone imitator can look similar, so testing hardness and examining inclusions are useful.

Field identification & locations

Common sources include Brazil, Switzerland, Madagascar, the United States, and Scotland. Look for quartz-like translucency, glassy luster, and resistance to scratching by a steel blade; definitive identification requires gemological testing.