sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with Goethite/Iron oxide inclusions
Hardness: 6.5-7.0 (Mohs scale), Color: Mustard yellow to brownish-gold, Luster: Dull or waxy when unpolished, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.58-2.91
- Hardness
- 6
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Physical properties
Hardness: 6.5-7.0 (Mohs scale), Color: Mustard yellow to brownish-gold, Luster: Dull or waxy when unpolished, Crystal Structure: Hexagonal (microcrystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.58-2.91
Formation & geological history
Formed through the infiltration of silica-rich fluids into sedimentary rock or volcanic ash, with iron oxides (goethite) providing the yellow coloration. It is found in deposits ranging from ancient Precambrian to more recent Cenozoic formations.
Uses & applications
Used primarily for lapidary work, jewelry (beads, cabochons), and as a decorative stone. Historically used for tools due to its hardness and sharp fracture edges.
Geological facts
Yellow jasper has been used since antiquity as a protection stone. It is a dense, opaque variety of chalcedony that gets its color from finely dispersed minerals within the quartz matrix.
Field identification & locations
Identify in the field by its opaque yellow color, extreme hardness (it will scratch glass), and smooth, curved (conchoidal) chip marks. Commonly found in riverbeds, deserts, or near volcanic regions globally.
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