sedimentary

Banded Chert

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Brown with gray/white banding, Luster: Waxy to vitreous, Structure: Microcrystalline/Cryptocrystalline, Fracture: Conchoidal

Hardness: 6

Identified July 19, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Brown with gray/white banding, Luster: Waxy to vitreous, Structure: Microcrystalline/Cryptocrystalline, Fracture: Conchoidal

Formation & geological history

Formed from the accumulation of silica-rich organic remains or chemical precipitation in marine or freshwater environments. Often found as nodules within limestone or dolostone beds.

Uses & applications

Historically used for stone tools (flintknapping); currently used in landscaping, as a lapidary material for tumbling, and in some construction aggregates.

Geological facts

Chert is a chemical sedimentary rock and is often referred to as flint when it is dark gray or black. Its conchoidal fracture creates extremely sharp edges, which is why it was the primary material for arrowheads and scrapers in prehistory.

Field identification & locations

Identify in the field by its smooth, waxy feel and ability to scratch glass. It often shows concentric or parallel banding and has a shell-like (conchoidal) fracture pattern when broken. Common globally.