sedimentary
Chert (Jasper variety)
Silicon Dioxide (SiO2)
Hardness: 6.5-7 Mohs; Color: Brownish-red to ochre; Luster: Waxy to vitreous; Crystal structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9
- Hardness
- 6
- Color
- Brownish-red to ochre
- Luster
- Waxy to vitreous
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Physical properties
Hardness: 6.5-7 Mohs; Color: Brownish-red to ochre; Luster: Waxy to vitreous; Crystal structure: Microcrystalline/cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9
Formation & geological history
Formed through the accumulation of silica-rich microfossils or precipitation from silica-rich fluids in sedimentary basins. This specimen shows water-worn rounding, likely from a fluvial or glacial environment.
Uses & applications
Historical use for stone tools (arrowheads); modern use in lapidary arts, jewelry (cabochons), and decorative landscaping.
Geological facts
Jasper is an opaque variety of chalcedony. In ancient times, it was believed to provide protection and was used extensively in cylinder seals and amulets.
Field identification & locations
Identify by its waxy luster, smooth texture, and inability to be scratched by a steel pocketknife. Most commonly found in riverbeds and gravel pits as stable, weather-resistant pebbles.
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