sedimentary

Flint (Chert Flake / Drill Tool)

SiO2 (Microcrystalline Quartz)

Hardness: 7 on Mohs scale; Color: Dark grey to blackish-brown; Luster: Waxy to vitreous; Crystal Structure: Cryptocrystalline; Cleavage: None (exhibits prominent conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Dark grey to blackish-brown
Luster: Waxy to vitreous

Identified July 26, 2026More sedimentary →

Explore Flint (Chert Flake / Drill Tool) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed as nodular masses or layers in sedimentary rocks, predominantly chalk and limestone formations, through chemical precipitation of silica or replacement of carbonate minerals.

Uses & applications

Historically used for knapping into prehistoric tools such as arrowheads, scrapers, drills, and spear points, as well as for spark generation in flintlock firearms and fire-starting. Today used in mineral collections, lapidary arts, and decorative landscaping.

Geological facts

This specimen shows clear signs of deliberate flaking (conchoidal retouching), resembling an worked stone drill, awl, or retouch flake created by flintknapping.

Field identification & locations

Identified by its fine grain, smooth waxy surface, shell-like (conchoidal) curved fractures, and sharp edges. Commonly found in limestone and chalk deposits globally, especially in Europe and North America.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Sedimentary Sandstone

Arenite (Sedimentary Rock)

sedimentary

Fossiliferous Concretion

Septarian Concretion containing Brachiopods/Crinoids

fossil

Shale

Shale (clastic sedimentary rock)

sedimentary

Shale

Argillaceous sedimentary rock

sedimentary

Mudstone

Argillite / Siliciclastic sedimentary rock

sedimentary