sedimentary

Chert (Flint/Jasper variety)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Tan, brown, and translucent cream; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7.

Hardness: 7 on Mohs scale
Color: Tan, brown, and translucent cream
Luster: Waxy to vitreous

Identified May 29, 2026More sedimentary →

Explore Chert (Flint/Jasper variety) 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 by the precipitation of silica from groundwater or the accumulation of siliceous skeletal remains (like diatoms or radiolarians). It occurs as nodules or layered beds within carbonate rocks like limestone.

Uses & applications

Historically used for stone tools and weapons due to sharp edges; industrial use as decorative stone, road surfacing, and as a component in ceramics.

Geological facts

Because it breaks with a conchoidal fracture creating sharp edges, it was the primary material for prehistoric arrowheads and scrapers. It is chemically very resistant to weathering.

Field identification & locations

Identify by its extreme hardness (cannot be scratched by a steel blade), waxy texture, and the way it flakes off in smooth curves (conchoidal fracture). Common in river beds and sedimentary outcrops.