sedimentary

Tumbled chert or jasper pebble

Microcrystalline quartz (SiO₂), commonly called chert; opaque varieties are jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; mustard-yellow to brown, opaque, with a dull to waxy luster and very fine-grained, noncrystalline texture. It shows irregular pale quartz or silica patches and lacks visible cleavage.

Identified August 26, 2026More sedimentary →

Explore Tumbled chert or jasper pebble 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

Formed when silica-rich groundwater replaced or cemented sediment, often from radiolarians, sponge remains, or volcanic ash; the exact geological age cannot be determined from the image. Its rounded shape indicates river, beach, or artificial tumbling abrasion.

Uses & applications

Used as a durable aggregate, roadstone, decorative stone, and historically for sharp-edged tools; attractive jasper is used in cabochons and carvings. This small tumbled piece has modest collector value.

Geological facts

Chert and jasper fracture conchoidally and can produce sharp edges; iron oxides commonly create yellow, red, and brown colors. The specimen may be a commercial tumbled jasper rather than naturally rounded chert.

Field identification & locations

Identify by its very fine texture, waxy appearance, high hardness, and inability to scratch with a steel knife easily; a streak or acid test is usually unhelpful. Common sources include sedimentary formations worldwide, especially North America, India, Madagascar, and Australia.