sedimentary
Chert / Jasper
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Brownish-tan; Luster: Waxy to dull; Crystal structure: Microcrystalline; Fracture: Conchoidal; Specific Gravity: 2.6-2.7
- Hardness
- 6
- Color
- Brownish-tan
- Luster
- Waxy to dull
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brownish-tan; Luster: Waxy to dull; Crystal structure: Microcrystalline; Fracture: Conchoidal; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation from groundwater within sedimentary layers. This specimen appears water-worn, likely from a fluvial or coastal environment.
Uses & applications
Historical toolmaking (flintknapping), industrial abrasives, landscaping, and ornamental stones.
Geological facts
Because of its high hardness and conchoidal fracture, chert was one of the most important materials for early humans to create sharp-edged tools and arrowheads.
Field identification & locations
Identify by its ability to scratch glass and smooth, waxy feel. Commonly found in riverbeds, glacial till, and embedded in limestone/dolomite outcrops.
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