sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) - variety of Chalcedony
Hardness: 6.5 - 7 (Mohs scale); Color: Mustard yellow to golden brown; Luster: Vitreous to waxy; Crystal structure: Trigonal (Microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58 - 2.91
- Hardness
- 6
- Color
- Mustard yellow to golden brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5 - 7 (Mohs scale); Color: Mustard yellow to golden brown; Luster: Vitreous to waxy; Crystal structure: Trigonal (Microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.58 - 2.91
Formation & geological history
Formed through the deposition of silica into cracks, veins, or sedimentary layers, often during the Jurassic or Cretaceous periods. Its yellow color comes from high iron inclusions (goethite or limonite).
Uses & applications
Commonly used in lapidary work for cabochons, beads, and decorative carvings. Also popular in jewelry, as garden stones, or as metaphysical 'healing' crystals.
Geological facts
Jasper is an opaque variety of chalcedony. Unlike true agate, it is almost always opaque due to the high amount of particulate mineral inclusions (up to 20% of the stone's mass).
Field identification & locations
Identify in the field by its waxy luster when wet, conchoidal (shell-like) fracture edges, and its ability to scratch glass. Commonly found in riverbeds, desert washes, and coastal areas in regions like Oregon, Madagascar, and South Africa.
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