sedimentary

Polished brown pebble, likely chert or jasper

Microcrystalline quartz (SiO₂), possibly iron-stained chert/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown to reddish-brown, opaque, fine-grained, with a waxy to dull luster and no visible cleavage. The smoothly tumbled shape and dark glossy edge indicate polishing or natural water wear.

Identified August 22, 2026More sedimentary →

Explore Polished brown pebble, likely chert 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

Chert forms when silica-rich fluids replace or cement sediment, commonly in limestone or marine sediments; jasper is an iron-rich opaque variety. Formation ages vary widely, from Precambrian to recent, while the rounded specimen was later transported and polished.

Uses & applications

Used for decorative objects, cabochons, beads, carvings, and occasionally tools; its small size and plain color give it modest ornamental value.

Geological facts

Chert breaks with smooth conchoidal fracture and can resemble flint; jasper differs mainly by its stronger iron staining and opaque appearance.

Field identification & locations

Look for a glassy edge, conchoidal fracture, uniform fine texture, and ability to scratch ordinary glass; common sources include river gravels and sedimentary regions worldwide. Exact identification requires a fresh edge or hardness/streak testing.