Rock Identifier
Yellow Jasper (Silicon Dioxide (SiO2) with goethite or limonite inclusions) — sedimentary
sedimentary

Yellow Jasper

Silicon Dioxide (SiO2) with goethite or limonite inclusions

Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow, ochre, gold; Luster: Dull or waxy when unpolished; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91

Hardness
6
Color
Mustard yellow, ochre, gold
Luster
Dull or waxy when unpolished
Identified More sedimentary

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Physical properties

Hardness: 6.5–7 on Mohs scale; Color: Mustard yellow, ochre, gold; Luster: Dull or waxy when unpolished; Crystal structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.91

Formation & geological history

Formed through the deposition of silica-rich fluids in volcanic ash or sedimentary layers. The yellow color comes from iron hydroxide minerals like goethite incorporated during formation.

Uses & applications

Used primarily in lapidary work, jewelry (cabochons), interior decoration, and as a pocket stone for collectors and spiritual practices.

Geological facts

Jasper is an opaque variety of chalcedony. It has been used since ancient times for seals, beads, and amulets. King John of England was famously buried with jasper items.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel knife) and its smooth, shell-like (conchoidal) fracture surface. Common in riverbeds and desert environments.