mineral

Tumbled smoky quartz pebble (probable)

Quartz, SiO₂; smoky variety colored by irradiation-related defects

AI-generated identification · may be incorrect

Translucent brown to gray-brown, vitreous luster, irregular conchoidal fractures, and no visible cleavage; hardness Mohs 7 and specific gravity about 2.65. The rounded shape indicates natural water wear or tumbling; inclusions or surface coating may affect the appearance.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Quartz crystallizes from silica-rich hydrothermal fluids and igneous pegmatites, commonly in cavities and veins; smoky coloration develops from natural radiation acting on aluminum impurities. Its exact geological age and locality cannot be determined from the image.

Uses & applications

Used as a decorative and lapidary stone, in carvings, jewelry, and mineral collections; quartz is also important industrially in glass, electronics, and abrasives.

Geological facts

The specimen may also be brown chalcedony, iron-stained quartz, or another dark silicate, since the image lacks diagnostic crystals or testing data.

Field identification & locations

Look for glassy luster, conchoidal fracture, lack of cleavage, and scratching ability against ordinary glass; a streak test, hardness test, specific gravity, and magnification would improve identification. Smoky quartz occurs worldwide, notably Brazil, Switzerland, Madagascar, and the United States.