sedimentary

Likely chert (flint)

Microcrystalline quartz, SiO₂

AI-generated identification · may be incorrect

The specimen appears tan-brown, dull to slightly waxy, and massive, with no visible crystals. Chert is Mohs 7, has a trigonal quartz structure at the microscopic scale, and typically lacks cleavage; this identification is tentative from the photo.

Identified October 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica accumulates and hardens in sedimentary settings, often as nodules in limestone or chalk. Its age depends on its host formation and cannot be determined from appearance alone.

Uses & applications

Chert has historically been used for sharp-edged tools and fire-starting; attractive pieces may be collected or used decoratively.

Geological facts

When struck, chert can fracture with curved, shell-like (conchoidal) surfaces and produce very sharp edges.

Field identification & locations

Look for hardness, a waxy-to-dull surface, and conchoidal fracture; common sources include sedimentary formations worldwide. The image alone does not establish the specimen’s identity with certainty.