mineral

Tumbled blue-gray chalcedony (likely common jasper/chalcedony)

Microcrystalline quartz, SiO₂ (chalcedony; exact variety uncertain from image)

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; blue-gray, opaque to slightly translucent, with a waxy to dull luster and no visible cleavage. The rounded shape indicates tumbling; pale brown/white patches may be iron oxides or included host rock.

Identified August 29, 2026More mineral →

Explore Tumbled blue-gray chalcedony (likely common jasper/chalcedony) 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

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, commonly during the Cenozoic or older geologic periods. The specimen was mechanically polished after collection.

Uses & applications

Used for inexpensive cabochons, beads, carvings, lapidary pieces, and decorative stone; common material has modest collector value.

Geological facts

Chalcedony is quartz composed of extremely fine intergrowths of quartz and moganite. Blue coloration can result from microscopic inclusions or light scattering rather than a distinct blue mineral.

Field identification & locations

Identify by its smooth waxy appearance, conchoidal fracture, lack of cleavage, and resistance to scratching glass; confirm with a hardness test. Common sources include Brazil, Uruguay, India, Madagascar, Mexico, and the western United States.