sedimentary

Chert (specifically Jasper/Flint)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale; Color: Brown, tan, reddish-brown; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Brown, tan, reddish-brown
Luster: Dull to waxy

Identified May 10, 2026More sedimentary →

Explore Chert (specifically Jasper/Flint) 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, reddish-brown; Luster: Dull to waxy; Crystal Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7

Formation & geological history

Formed through the accumulation of silica-rich organic remains or chemical precipitation from groundwater within sedimentary rock layers, predominantly during various geological eras from the Precambrian to Cenezoic.

Uses & applications

Historically used for stone tools and weapons (arrowheads); currently used in jewelry (as jasper), industrial abrasives, and as decorative landscaping stone.

Geological facts

Chert has been essential to human development as it was the primary material for the Stone Age tool industry due to its predictable conchoidal fracturing which produces sharp edges.

Field identification & locations

Identify in the field by its smooth, glass-like fracture surfaces, extreme hardness (it will scratch steel), and waxy feel. Commonly found in limestone or chalk deposits as nodules or layered beds.