sedimentary

Chert or microcrystalline quartz fragment

Chert; cryptocrystalline SiO₂, possibly chalcedony-rich

AI-generated identification · may be incorrect

Small angular fragment with pale cream-orange color, dull to slightly waxy luster, and likely conchoidal fracture; quartz hardness is about Mohs 7, with no cleavage. Exact texture and density cannot be confirmed from the image alone.

Identified September 19, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica-rich groundwater or biogenic silica precipitates and replaces sediments, commonly in limestone or thin marine beds. Its age varies widely, from Precambrian to modern sedimentary deposits.

Uses & applications

Used historically for sharp tools and arrowheads; attractive pieces are collected, and some varieties are used as decorative stone. This fragment has negligible commercial value.

Geological facts

The sharp, curved fracture surfaces and very fine grain are characteristic of chert, though the specimen may also be weathered quartz or chalcedony.

Field identification & locations

Test by attempting to scratch glass: true chert usually does so, while calcite will not. Common locations include limestone regions, gravel beds, and exposed sedimentary formations; value is typically $0-$5 for a loose common fragment.