sedimentary

Weathered iron-rich chert or jasper

Microcrystalline quartz (SiO₂), variably stained by iron oxides

AI-generated identification · may be incorrect

Opaque reddish-brown to gray, earthy to dull luster, conchoidal-looking fracture and no visible cleavage; Mohs hardness about 6.5–7, though the rough weathered surface obscures these traits. The rounded form suggests natural abrasion or weathering.

Identified August 29, 2026More sedimentary →

Explore Weathered iron-rich 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

Likely silica-rich sediment chemically precipitated or replacing sediment, later colored by hematite/goethite; exact age and locality cannot be determined from the photograph. Chert and jasper commonly form in marine sediments, volcanic terrains, and hydrothermal settings.

Uses & applications

Common material is used for decorative stone, carvings, cabochons, and occasionally aggregate; attractive jasper may be used in jewelry. This specimen appears primarily a field or teaching specimen.

Geological facts

Iron oxides produce the red-brown coloration, while microcrystalline quartz gives chert its toughness. Distinguishing jasper from iron-stained chert often requires examining texture and thin sections.

Field identification & locations

Look for glassy or waxy luster, very hard edges that scratch ordinary glass, conchoidal fracture, and lack of fizz with dilute acid. Common worldwide, especially in sedimentary basins and volcanic regions.