sedimentary
Yellow Jasper
Silicon dioxide (SiO2) with iron oxide inclusions
Hardness: 6.5-7 on Mohs scale; Color: Mustard yellow to brownish-yellow with darker banding or mottling; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
- Hardness
- 6
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Mustard yellow to brownish-yellow with darker banding or mottling; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.91
Formation & geological history
Formed through the infiltration of silica-rich fluids into volcanic ash or fine-grained sediments. Over time, these fluids solidify into chert/jasper, with the yellow color derived from hydrated iron (goethite) or limonite inclusions.
Uses & applications
Used primarily in lapidary work for cabochons, beads, and decorative ornaments. It is also popular in the metaphysical community as a 'grounding' stone and used as a durable material for stone tools in prehistoric times.
Geological facts
Jasper was a favorite gem in the ancient world; its name can be traced back in Arabic, Persian, Greek, and Latin. Yellow jasper specifically is often found in riverbeds as rounded 'river stones' due to its high hardness and resistance to erosion.
Field identification & locations
Identify in the field by its opaque nature (unlike agate which is translucent), its smooth, waxy feel when wet, and its inability to be scratched by a steel knife. Common in areas with ancient volcanic activity or river deposits.
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