sedimentary

Chert (specifically as a lithic artifact/projectile point)

Chert (Silicon dioxide, SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale); Color: Mottled gray, tan, and blue-gray with earthy inclusions; Luster: Waxy to dull; Crystal structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.65.

Hardness: 7 (Mohs scale)
Color: Mottled gray, tan, and blue-gray with earthy inclusions
Luster: Waxy to dull

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like radiolaria or diatoms) or chemical precipitation in marine environments; age varies by deposit, typically Paleozoic to Mesozoic era formations.

Uses & applications

Historically used for tools and weapons due to sharp conchoidal edges; currently valued for archaeological study, flintknapping, and amateur collecting.

Geological facts

This specimen has been worked by humans into a stone tool, known as a 'lithic artifact.' Notice the 'flake scars' where the material was struck to create sharp edges and a notched base for hafting to a shaft.

Field identification & locations

Identify in the field by looking for translucent edges, a 'clinking' sound when tapped, and signs of intentional shaping (flaking). Common in limestone-rich regions of the American Midwest and Southeast.