sedimentary
Chert (Jasper)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7.0 (Mohs scale), Color: Brownish-orange to rust, Luster: Waxy to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
- Hardness
- 6
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Physical properties
Hardness: 6.5-7.0 (Mohs scale), Color: Brownish-orange to rust, Luster: Waxy to dull, Crystal structure: Trigonal (microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed by the accumulation of silica-rich organic remains or chemical precipitation in sedimentary environments. Its color is often due to iron oxide inclusions.
Uses & applications
Historically used for stone tools due to sharp fracture edges; currently used for landscaping, tumbled stones, and lapidary work.
Geological facts
This specimen appears to be a water-worn, iron-stained chert pebble. Chert is so hard it can create sparks when struck against steel.
Field identification & locations
Identify by its waxy luster, smoothness, and inability to be scratched by a steel pocketknife. Common in riverbeds and on beaches worldwide.
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