sedimentary

Likely chert (flint) fragment

Microcrystalline quartz (SiO₂), possibly iron-stained chert

AI-generated identification · may be incorrect

Tan to brown, dull to waxy luster, with irregular fractures and no visible crystals; quartz hardness is about 7 Mohs and it has no cleavage. The image alone cannot confirm the identification or specific gravity.

Identified October 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica accumulates and hardens in sedimentary settings, often replacing carbonate material; its age depends on the host formation and cannot be determined from the specimen alone.

Uses & applications

Chert has historically been used for tools and, when attractive, for lapidary pieces; ordinary fragments have little commercial use.

Geological facts

Freshly broken chert commonly shows sharp, curved (conchoidal) fracture surfaces, making it useful for identifying worked stone tools.

Field identification & locations

Look for a very hard, fine-grained texture and sharp fracture edges; chert occurs in sedimentary beds and nodules worldwide. The pictured piece may also be another weathered stone, so a fresh-break or hardness test would help.