sedimentary

Chert (often called Flint or Jasper)

Microcrystalline or cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Brown, tan, and reddish-orange due to iron oxides. Luster: Waxy to dull. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Brown, tan, and reddish-orange due to iron oxides
Luster: Waxy to dull

Identified July 19, 2026More sedimentary →

Explore Chert (often called Flint or Jasper) 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 on Mohs scale. Color: Brown, tan, and reddish-orange due to iron oxides. Luster: Waxy to dull. Crystal structure: Cryptocrystalline. Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through the accumulation of siliceous remains of organisms or chemical precipitation. This specific sample shows banding indicative of varying mineral impurity deposition in a sedimentary environment.

Uses & applications

Historically used for stone tools (knapping) due to its sharp edges; currently used for road surfacing, lapidary work, and landscaping.

Geological facts

Chert was one of the most vital materials for early humans because its conchoidal fracture allows it to be shaped into razor-sharp arrowheads and knives.

Field identification & locations

Identify in the field by its smooth, waxy texture and curved, shell-like (conchoidal) fracture patterns when broken. Commonly found in limestone and chalk deposits.