sedimentary

Possible iron-rich chert or flint fragment

Microcrystalline quartz (SiO₂), likely hematite/goethite-bearing

AI-generated identification · may be incorrect

Dark brown to reddish-brown, opaque, earthy to slightly waxy luster, and fine-grained with no visible crystals; quartz hardness is about 7 Mohs, though the rough surface may be softer from weathering. Its pointed, tapered shape and apparent conchoidal fracturing are consistent with chert or a worked flint fragment.

Identified August 20, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica replaces or accumulates within sediment, commonly in limestone, and may acquire red-brown coloration from iron oxides. Its exact geological age cannot be determined from the photograph; chert occurs from Precambrian to recent deposits.

Uses & applications

Used historically for cutting tools and fire-starting, and today mainly as a collector or educational specimen; crushed chert can serve as aggregate.

Geological facts

Conchoidal fracture produces sharp edges and curved surfaces rather than cleavage. The shape may indicate intentional knapping, but the image alone cannot confirm human workmanship.

Field identification & locations

Look for glassy curved fracture, very fine texture, and inability to scratch it with a steel knife; reddish streaks suggest iron oxides. Common in limestone and gravel deposits worldwide.