mineral

Tumbled white chalcedony (likely milky quartz)

Chalcedony, cryptocrystalline SiO₂; possibly common quartz or white agate

AI-generated identification · may be incorrect

Small rounded, polished pebble with a milky-white, translucent appearance and waxy-to-vitreous luster. Quartz-group hardness is about 6.5–7 Mohs, with no visible cleavage and conchoidal fracture; density is approximately 2.60 g/cm³.

Identified September 8, 2026More mineral →

Explore Tumbled white chalcedony (likely milky quartz) 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 deposits microscopic quartz fibers in cavities, fractures, or volcanic rocks; the specimen was subsequently tumbled and polished. The exact geological age and source cannot be determined from the photograph.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and lapidary collections; larger patterned varieties are sold as agate. This small common piece has modest commercial value.

Geological facts

Chalcedony is quartz at the chemical level but has a microcrystalline structure, giving it a smoother, waxier look than ordinary quartz crystals.

Field identification & locations

Identify it by its rounded polish, even milky translucence, hardness, and lack of visible crystal faces; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, Uruguay, India, Madagascar, and the western United States.