sedimentary

Chert (specifically a Worked Flint/Knapped Flake)

Chert / Flint (Microcrystalline Quartz, SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: Brownish-grey/Tan, Luster: Waxy to dull, Crystal Structure: Cryptocrystalline, Cleavage: None (displays prominent conchoidal fracture with ripple-like undulations), Specific Gravity: 2.65

Identified March 30, 2026More sedimentary →

Explore Chert (specifically a Worked Flint/Knapped Flake) in the encyclopedia →

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Physical properties

Formation & geological history

Formed through the accumulation of silica-rich microfossils (like radiolarians or diatoms) or chemical precipitation within limestone/chalk beds. The specimen shows secondary 'working' or fracturing, possibly as a lithic flake from prehistoric tool-making efforts.

Uses & applications

Historically used for stone tools (axes, scrapers, arrowheads) and strike-a-lights. Modernly used as a road aggregate, in glass manufacturing, or as archaeological artifacts for study.

Geological facts

Flint was one of the first 'high-tech' materials for humanity, allowing for the creation of sharp edges for survival. The 'ripples' seen on the surface are called 'eraillure scars' or compression rings, typical of a hard-hammer percussion strike.

Field identification & locations

Identify by its 'shell-like' (conchoidal) fracture pattern and ability to scratch glass. Commonly found in chalk or limestone deposits. In the field, look for sharp edges and bulbs of percussion that indicate human manipulation.