sedimentary
Chert / Yellow Jasper
Silicon Dioxide (SiO2)
Hardness: 6.5-7 (Mohs); Color: Yellow to ochre with waxy luster; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 6
- Color
- Yellow to ochre with waxy luster
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Yellow to ochre with waxy luster; Crystal Structure: Microcrystalline quartz; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the accumulation of silica-rich microfossils or chemical precipitation from hydrothermal fluids in sedimentary basins. The yellow color is due to iron oxide (limonite) inclusions.
Uses & applications
Historically used for stone tools and fire-starting (flint); currently used in jewelry (lapidary), as decorative stones, and in construction aggregate.
Geological facts
Because of its harness and conchoidal fracture, it was the primary material for arrowheads and scrapers in pre-industrial societies. Jasper is often called the 'ultimate nurturer' in metaphysical circles.
Field identification & locations
Identify by its waxy texture and sharp, shell-like (conchoidal) breaking pattern. It will easily scratch glass but cannot be scratched by a steel nail. Commonly found in riverbeds or limestone deposits.
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