sedimentary

Chert (Flint Nodules)

Silicon dioxide (SiO2)

Hardness: 7 (Mohs); Color: Gray, tan, or white; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs)
Color: Gray, tan, or white
Luster: Waxy to dull

Identified July 19, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs); Color: Gray, tan, or white; Luster: Waxy to dull; Crystal structure: Microcrystalline/Cryptocrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed through the accumulation of silica-rich organic remains (like radiolarians or diatoms) or chemical precipitation in marine environments; commonly found in limestone or chalk beds.

Uses & applications

Historically used for stone tools and weapons (arrowheads); currently used in road construction, as decorative landscaping stone, and for fire-starting in survival kits.

Geological facts

Flint is a variety of chert. When struck against steel, it creates sparks due to the friction oxidizing iron particles. It was the primary material for the 'Stone Age' technological revolution.

Field identification & locations

Identify by its smooth, waxy surface and characteristic shell-like (conchoidal) fractures. Often found as rounded nodules in chalk or limestone cliffs or as weathered pebbles in riverbeds.