sedimentary

Yellow-brown chert or silicified rock fragment

Microcrystalline quartz (SiO₂), likely chert or chalcedony-rich material

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, dull to waxy luster, opaque to translucent yellow-brown color, and no visible cleavage; conchoidal fracture is common. The image appears to show a small weathered, possibly flaked fragment with a lighter silica-rich interior.

Identified September 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement sediment, often from biogenic silica in marine limestone; ages range from Precambrian to recent. Exact age and variety cannot be determined from the photograph.

Uses & applications

Used for tools, aggregate, decorative stone, and lapidary items; attractive translucent pieces may be polished, though this specimen appears low-grade.

Geological facts

Chert can preserve fossils and commonly breaks with sharp conchoidal edges. Yellow coloration may result from iron oxides or hydroxides.

Field identification & locations

Identify by its glassy-to-waxy appearance, hardness, resistance to scratching by steel, and conchoidal fracture; common worldwide, especially in limestone and sedimentary formations. A definitive identification would require a close examination or hardness and streak tests.