
sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with goethite or limonite inclusions
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow, ochre, gold; Luster: Dull or waxy when unpolished; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91
- Hardness
- 6
- Color
- Mustard yellow, ochre, gold
- Luster
- Dull or waxy when unpolished
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow, ochre, gold; Luster: Dull or waxy when unpolished; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91
Formation & geological history
Formed through the deposition of silica-rich fluids in volcanic ash or sedimentary layers. The yellow color comes from iron hydroxide minerals like goethite incorporated during formation.
Uses & applications
Used primarily in lapidary work, jewelry (cabochons), interior decoration, and as a pocket stone for collectors and spiritual practices.
Geological facts
Jasper is an opaque variety of chalcedony. It has been used since ancient times for seals, beads, and amulets. King John of England was famously buried with jasper items.
Field identification & locations
Identify in the field by its hardness (cannot be scratched by a steel knife) and its smooth, shell-like (conchoidal) fracture surface. Common in riverbeds and desert environments.
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