sedimentary

Chert (Jasper/Flint variety)

Microcrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs scale), Color: tan, brown, and yellowish-orange due to iron oxides, Luster: waxy to dull, Crystal Structure: trigonal (microcrystalline), Cleavage: none (conchoidal fracture), Specific Gravity: 2.65

Identified June 25, 2026More sedimentary →

Explore Chert (Jasper/Flint 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 through the accumulation of silica-rich organic remains or chemical precipitation in sedimentary basins. The iron staining (limonite/hematite) suggests secondary groundwater interaction and weathering.

Uses & applications

Historically used for stone tools and weapons due to its sharp conchoidal fracture. Modern uses include landscaping, road base, and occasionally as semi-precious gemstones (jasper) in jewelry.

Geological facts

Chert is so hard it can scratch steel and glass. It was used by ancient civilizations to start fires by striking it against steel to create sparks, a property shared with its variety, flint.

Field identification & locations

Identify by its waxy luster, jagged/curved (conchoidal) breaking pattern, and extreme hardness. Often found in riverbeds or within limestone and chalk deposits.