mineral

Smoky quartz pebble (probable)

Quartz, silicon dioxide (SiO₂), likely smoky variety

AI-generated identification · may be incorrect

Dark gray-brown, translucent edges, vitreous-to-waxy luster, conchoidal fracture, and no obvious cleavage; Mohs hardness 7, specific gravity about 2.65. The rounded shape indicates natural abrasion or tumbling, and surface coating/weathering may obscure the crystals.

Identified August 29, 2026More mineral →

Explore Smoky quartz pebble (probable) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Smoky quartz forms when natural radiation or trace aluminum colors quartz crystals in granitic pegmatites, hydrothermal veins, and metamorphic rocks. Individual crystals may be Precambrian to recent; the pebble itself was later eroded and transported.

Uses & applications

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

Geological facts

Smoky coloration ranges from pale gray to nearly black and can fade with strong heat or sunlight. The specimen’s identity is provisional because the image does not show diagnostic crystal faces or a clear internal structure.

Field identification & locations

Look for glassy luster, conchoidal fracture, translucency, and inability to scratch it with a steel knife; it should scratch ordinary glass. Common sources include Brazil, Switzerland, the United States, Madagascar, and Scotland.