sedimentary
Yellow Jasper (Chalcedony)
Silicon Dioxide with Iron inclusions (SiO2)
Hardness: 6.5–7 (Mohs); Color: Mustard yellow to brownish-gold; Luster: Dull to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.9
- Hardness
- 6
- Color
- Mustard yellow to brownish-gold
- Luster
- Dull to waxy
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Physical properties
Hardness: 6.5–7 (Mohs); Color: Mustard yellow to brownish-gold; Luster: Dull to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.9
Formation & geological history
Formed from the precipitation of silica from groundwater or volcanic fluids in the cracks and cavities of other rocks. Its yellow color comes from the presence of iron (goethite or limonite) during formation.
Uses & applications
Used primarily as a gemstone for jewelry (cabochons, beads), decorative carvings, and in alternative medicine/crystal healing practices.
Geological facts
Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. It was highly valued in the ancient world, frequently used in seals and amulets.
Field identification & locations
Identify in the field by its opacity (it does not transmit light like agate), high hardness (cannot be scratched by a steel knife), and characteristic waxy luster when broken. Common in riverbeds and coastal areas.
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