sedimentary
Chert
Sedimentary Cryptocrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness: 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
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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.
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