sedimentary
Chert (Brown Jasper)
Microcrystalline Quartz (SiO2)
AI-generated identification · may be incorrectHardness 6.5–7 on Mohs scale; waxy to dull luster, conchoidal fracture, and opaque brown or tan color.
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Physical properties
Hardness 6.5–7 on Mohs scale; waxy to dull luster, conchoidal fracture, and opaque brown or tan color.
Formation & geological history
Formed through the precipitation of silica from groundwater or biogenic marine ooze within sedimentary rock layers.
Uses & applications
Used historically for flintknapping into sharp tools and currently as decorative stone, landscape gravel, or lapidary material.
Geological facts
Due to its predictable conchoidal fracture and hardness, brown chert was one of humanity's earliest tool-making materials.
Field identification & locations
Identify by its hardness (scratches glass), lack of visible grains, smooth waxy feel, and sharp shell-like fracture edges.
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