sedimentary

Chert (Flint)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Brown, yellowish, gray, waxy luster; Crystal Structure: Cryptocrystalline/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 (Mohs scale)
Color: Brown, yellowish, gray, waxy luster

Identified June 22, 2026More sedimentary →

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Physical properties

Hardness: 7 (Mohs scale); Color: Brown, yellowish, gray, waxy luster; Crystal Structure: Cryptocrystalline/Microcrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Formation & geological history

Formed through the precipitation of silica from groundwater or the accumulation of siliceous skeletal remains (diatoms, radiolarians) in marine environments. Often found as nodules in chalk or limestone deposits.

Uses & applications

Historically used for stone tools and weapons due to its sharp edges. Currently used in road construction, as an abrasive, and occasionally for lapidary work.

Geological facts

France is famous for its high-quality flint, which was essential for prehistoric civilizations in the region. The Grand-Pressigny region in France was a major center for flint export during the Neolithic era.

Field identification & locations

Identify in the field by its smooth, waxy feel, conchoidal (shell-like) fracture edges, and its ability to scratch glass. It is commonly found in riverbeds or coastal cliffs in France, especially near limestone formations.