sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron hydroxides
Hardness: 6.5-7 (Mohs); Color: Mustard yellow to ochre; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Gravity: 2.58-2.91
- Hardness
- 6
- Color
- Mustard yellow to ochre
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Mustard yellow to ochre; Luster: Dull to waxy; Structure: Microcrystalline; Cleavage: None (conchoidal fracture); Gravity: 2.58-2.91
Formation & geological history
Formed through the accumulation of silica-rich microfossils or volcanic ash that undergoes petrification. The yellow color comes from Goethite or other iron inclusions during the sedimentary process.
Uses & applications
Commonly used for lapidary work, cabochons for jewelry, small carvings, and as a decorative landscaping stone due to its durability and ability to take a high polish.
Geological facts
Jasper is an opaque variety of chalcedony. In ancient times, yellow jasper was often associated with protection and as a 'nurturing' stone in various folklore traditions.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife), smooth waxy feel, and conchoidal (shell-like) fracture patterns. Found in riverbeds or gravel deposits globally.
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