sedimentary

Banded chert or jasper

Microcrystalline quartz (SiO₂), likely chalcedony with iron-oxide impurities

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown, gray, and cream banding; waxy to dull luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The rough, weathered fragment appears naturally stone-like.

Identified September 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement fine sediment, often producing iron-stained bands; ages range from Precambrian to younger sedimentary deposits. Exact identification and age require testing or locality information.

Uses & applications

Used as a decorative stone, lapidary material, cabochons, beads, and occasionally aggregate; this small rough piece has little commercial value.

Geological facts

Chert and jasper are varieties of microcrystalline quartz; “jasper” generally refers to opaque, impurity-rich material, while chert is often gray or less colorful.

Field identification & locations

Identify by its very hard surface, glassy/conchoidal fracture, lack of cleavage, and inability to scratch it with a steel knife; common in sedimentary formations, river gravels, and iron-rich terrains. A streak, hardness, and close-up examination would distinguish it from quartzite or weathered shale.