sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron hydroxides
Hardness: 6.5-7 (Mohs scale); Color: Yellow, mustard, or tan; Luster: Dull to greasy (waxy when polished); Crystal Structure: Hexagonal (microcrystalline/cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9
- Hardness
- 6
- Color
- Yellow, mustard, or tan
- Luster
- Dull to greasy (waxy when polished)
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Yellow, mustard, or tan; Luster: Dull to greasy (waxy when polished); Crystal Structure: Hexagonal (microcrystalline/cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9
Formation & geological history
Formed through the deposition of silica from volcanic ash or water saturation, often in hydrothermal veins or as nodules in sedimentary rocks. The yellow coloration comes from the inclusion of Goethite or other iron oxides.
Uses & applications
Used primarily in lapidary arts for cabochons, beads, and ornemental carvings. Used in jewelry and as an 'earth-tone' decorative stone.
Geological facts
Jasper is an opaque variety of chalcedony. In ancient times, yellow jasper was believed to provide spiritual protection and guidance on long journeys.
Field identification & locations
Identify in the field by its opacity (unlike translucent agate), its conchoidal (shell-like) fracture pattern, and its inability to be scratched by a steel knife. Commonly found in riverbeds and desert environments.
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