sedimentary

Chert (Arrowhead/Projectile Point)

Microcrystalline quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Brown, gray, black; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6

Hardness: 6
Color: Brown, gray, black
Luster: Waxy to dull

Identified June 23, 2026More sedimentary →

Explore Chert (Arrowhead/Projectile Point) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7 Mohs; Color: Brown, gray, black; Luster: Waxy to dull; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6

Formation & geological history

Formed as nodules or beds in limestone/chalk through the accumulation of siliceous remains or chemical precipitation. This specific specimen was later anthropogenically modified by flintknapping.

Uses & applications

Historically used for tools and weapons; currently valued as an archaeological artifact and for lapidary use.

Geological facts

Chert was one of the first materials used by early humans for tools because its conchoidal fracture produces extremely sharp edges. This specimen is an arrowhead, specifically a projectile point.

Field identification & locations

Identify by its waxy luster, hardness (scratches glass), and distinct shell-like (conchoidal) fracture scars from knapping. Found globally in sedimentary basins.