sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 (Mohs); Color: Mustard yellow to brownish-yellow; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9
- Hardness
- 6
- Color
- Mustard yellow to brownish-yellow
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Mustard yellow to brownish-yellow; Luster: Vitreous to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.9
Formation & geological history
Formed through the infiltration of silica-rich fluids into sediment or volcanic ash, eventually hardening into microcrystalline quartz. Usually dates back to millions of years ago in volcanic or sedimentary environments.
Uses & applications
Widely used as a gemstone for jewelry, decorative carvings, and in alternative healing practices (metaphysical uses). Historically used for tools due to its durability.
Geological facts
The yellow color is specifically caused by the presence of iron oxide (goethite or limonite). It is often found as smooth water-worn pebbles in riverbeds or coastal areas.
Field identification & locations
Identify in the field by its opaque nature, smooth waxy texture, and its inability to be scratched by a steel knife. Common in the Western United States, South Africa, and Brazil.
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