sedimentary

Chert (specifically Flint or Nodular Chert)

Silicon dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Tan, beige, or cream; Luster: Dull to waxy; Structure: Microcrystalline; Fracture: Conchoidal (shell-like curves)

Hardness: 7 on Mohs scale
Color: Tan, beige, or cream
Luster: Dull to waxy

Identified May 24, 2026More sedimentary →

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Physical properties

Hardness: 7 on Mohs scale; Color: Tan, beige, or cream; Luster: Dull to waxy; Structure: Microcrystalline; Fracture: Conchoidal (shell-like curves)

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments, often as nodules within limestone or chalk beds.

Uses & applications

Historically used for stone tools (knapping) and fire-starting; currently used for decorative stone, landscaping, and as a raw material for ceramics and glass.

Geological facts

Chert breaks with a very sharp edge, which made it the primary material for arrowheads and spears for thousands of years. It is essentially a non-crystalline form of quartz.

Field identification & locations

Identify by its 'flinty' waxy surface and conchoidal fracture patterns. These specimens appear to be weathered nodules collected from a gravel pit or limestone deposit.