sedimentary
Yellow Jasper
Silicon Dioxide (SiO2) with iron oxide impurities
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to brownish-yellow, Luster: Vitreous to waxy, Crystal Structure: Trigonal (Microcrystalline), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.58-2.91
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Mustard yellow to brownish-yellow, Luster: Vitreous to waxy, Crystal Structure: Trigonal (Microcrystalline), Cleavage: None (Conchoidal fracture), Specific Gravity: 2.58-2.91
Formation & geological history
Forms through the deposition of silica-rich fluids in volcanic ash or sedimentary beds, often during the Proterozoic to Cenozoic eras. The yellow color is caused by the presence of goethite or limonite (iron oxides).
Uses & applications
Primarily used for lapidary work including cabochons, beads, and tumbled stones. Historically used for ornaments and spiritual amulets.
Geological facts
Jasper is an opaque variety of chalcedony. Historically, it was known as a stone of endurance and protection. Specimens displaying distinct patterning are often called 'Picture Jasper'.
Field identification & locations
Identify in the field by its opacity (it will not let light through even at thin edges), smooth conchoidal fracture, and inability to be scratched by a steel knife. Commonly found in riverbeds and desert environments.
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