sedimentary

Weathered chert or flint pebble

Microcrystalline quartz (SiO₂), likely chert/flint with possible carbonate or quartz vein

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown to olive-gray, dull to waxy luster, very fine-grained cryptocrystalline structure, and no visible cleavage. The pale rough band may be a quartz-rich fracture or weathered coating; the image alone cannot distinguish chert from other silica-rich pebble types confidently.

Identified August 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica-rich fluids or biogenic silica replaces sediment, commonly in limestone or marine sedimentary beds; ages range from Precambrian to recent. This rounded specimen was likely shaped by stream or beach abrasion.

Uses & applications

Used historically for sharp tools and fire-starting, and today mainly as a lapidary, teaching, or collection specimen; it has little industrial value at this size.

Geological facts

Fresh chert typically breaks with conchoidal fractures and sharp edges. Flint is generally a dark, compact variety of chert, while brown varieties are often called jasper-like chert.

Field identification & locations

Common in sedimentary terrains worldwide, especially chalk, limestone, and gravel deposits. Test cautiously with a steel file or glass: genuine chert should scratch glass; inspect a fresh edge for waxy texture and conchoidal fracture.