sedimentary
Chert
Sedimentary Cryptocrystalline Quartz (SiO2)
Hardness: 7 Mohs scale; Color: Brown, grey, and waxy green; Luster: Vitreous to waxy; Texture: Fine-grained, dense, and displays conchoidal fracture.
- Hardness
- 7 Mohs scale
- Color
- Brown, grey, and waxy green
- Luster
- Vitreous to waxy
Identified More sedimentary →
Explore Chert in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 Mohs scale; Color: Brown, grey, and waxy green; Luster: Vitreous to waxy; Texture: Fine-grained, dense, and displays conchoidal fracture.
Formation & geological history
Formed via the accumulation of silica-rich organic remains (like radiolaria or diatoms) or chemical precipitation from groundwater within sedimentary layers.
Uses & applications
Historically used for stone tools (flint knapping); currently used in road construction, as an abrasive, and by crystal collectors for lapidary work.
Geological facts
Chert has been used by humans for millions of years to create sharp-edged tools. Variations include flint (dark), jasper (red), and agate (banded).
Field identification & locations
Identify in the field by its extreme hardness (scratches glass), waxy feel, and sharp, shell-like (conchoidal) edges when broken. Frequently found as nodules in limestone.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Shale
Shale (clastic sedimentary rock)
sedimentary
Brown Sandstone (River Rock)
Arenite
sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary
Cone-in-cone structure (Limestone)
Cone-in-cone structure (Secondary Sedimentary Structure)
sedimentary