sedimentary
Chert (Jasper variety)
Microcrystalline Quartz (SiO2)
Hardness: 6.5-7 on Mohs scale; Color: Brownish-yellow and dark grey; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
- Hardness
- 6
- Color
- Brownish-yellow and dark grey
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Brownish-yellow and dark grey; Luster: Dull to waxy; Structure: Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65
Formation & geological history
Formed through the accumulation of silica-rich organic remains or chemical precipitation in marine environments. This specimen appears water-worn, likely from a river or beach deposit.
Uses & applications
Historically used for stone tools due to sharp edges; currently used for decorative gravel, landscaping, and as a lapidary material for tumbling and cabochons.
Geological facts
Chert is essentially the same mineral as flint, but the name 'Jasper' is applied to opaque varieties. It is extremely durable and chemically resistant to weathering.
Field identification & locations
Identifiable in the field by its hardness (will scratch glass), conchoidal (shell-like) fracture patterns, and smooth, waxy surface when wet. Commonly found in gravel pits and along shorelines.
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