sedimentary

Chert (with possible fossils)

Microcrystalline quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale), Color: tan, grey, or off-white with waxy luster. Dense, microcrystalline structure with conchoidal fracture patterns.

Hardness: 6
Color: tan, grey, or off-white with waxy luster

Identified March 16, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: tan, grey, or off-white with waxy luster. Dense, microcrystalline structure with conchoidal fracture patterns.

Formation & geological history

Formed through the accumulation of silica in marine environments, often replacing calcium carbonate in limestone. Its geological age can range from Precambrian to Cenozoic.

Uses & applications

Historically used for stone tools and fire-starting (flint). Currently used as an aggregate in construction or as road metal; decorative landscape gravel.

Geological facts

This specimen appears to be a stream-worn or weathered chert nodule containing circular impressions that may be crinoid stem fragments or trace fossil molds.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by steel) and waxy luster. Found globally in limestone formations and alluvial deposits. Search for fossils on weathered surfaces.