sedimentary

Banded chert (likely jasper/chalcedony-rich stone)

Microcrystalline quartz, SiO₂, with iron-oxide impurities

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; pink, gray, cream, and brown wavy bands; dull to waxy luster; very fine-grained, cryptocrystalline quartz with no visible cleavage. It likely has a dense, opaque appearance and conchoidal fracture.

Identified August 14, 2026More sedimentary →

Explore Banded chert (likely jasper/chalcedony-rich stone) 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 fine sediment, often from marine biological silica; iron oxides create the reddish-brown colors. Precise age cannot be determined from the image and may range from Paleozoic to younger.

Uses & applications

Used as decorative stone, cabochons, beads, carvings, and lapidary material; exceptionally fine varieties may be sold as jasper. It is also historically useful for sharp-edged tools.

Geological facts

The specimen’s curved, ribbon-like bands and waxy surface are characteristic of jaspery chert rather than crystalline granite or marble. A fresh fracture should be sharp and glass-like.

Field identification & locations

Common in sedimentary terrains, river gravels, and weathered outcrops worldwide. Confirm with a hardness test against glass and inspection for conchoidal fracture; avoid confusing it with dyed or polished agate.