mineral

Polished/tumbled chalcedony (likely agate or jasper)

Microcrystalline quartz, SiO₂; possibly iron-oxide-bearing jasper or agate

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; waxy to vitreous luster; gray, cream, tan, and brown coloration with iron-oxide staining. Usually cryptocrystalline and lacks visible cleavage, with conchoidal fracture; approximate specific gravity 2.6.

Identified August 28, 2026More mineral →

Explore Polished/tumbled chalcedony (likely agate or jasper) 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 or fractures in volcanic rocks, later developing fibrous quartz and colored mineral bands; most specimens formed during the Cenozoic or Mesozoic, depending on locality.

Uses & applications

Used as a decorative stone, cabochon, bead, carving, and inexpensive lapidary material; polished pieces have modest collector value.

Geological facts

The image shows a shaped and polished specimen, so natural surface texture and diagnostic banding are partly obscured. The pale translucent areas may be chalcedony, while brown zones likely contain iron oxides.

Field identification & locations

Common sources include Brazil, Uruguay, India, Madagascar, Mexico, and the western United States. Identify with a glass-scratching test, waxy luster, translucency at thin edges, and absence of cleavage; exact variety requires close examination.