sedimentary

Yellow Jasper (Chalcedony)

Silicon Dioxide with Iron inclusions (SiO2)

Hardness: 6.5–7 (Mohs); Color: Mustard yellow to brownish-gold; Luster: Dull to waxy; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6–2.9

Hardness: 6
Color: Mustard yellow to brownish-gold
Luster: Dull to waxy

Identified April 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the precipitation of silica from groundwater or volcanic fluids in the cracks and cavities of other rocks. Its yellow color comes from the presence of iron (goethite or limonite) during formation.

Uses & applications

Used primarily as a gemstone for jewelry (cabochons, beads), decorative carvings, and in alternative medicine/crystal healing practices.

Geological facts

Jasper is an opaque variety of chalcedony. The name comes from the Greek word 'iaspis', meaning 'spotted stone'. It was highly valued in the ancient world, frequently used in seals and amulets.

Field identification & locations

Identify in the field by its opacity (it does not transmit light like agate), high hardness (cannot be scratched by a steel knife), and characteristic waxy luster when broken. Common in riverbeds and coastal areas.

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Sandstone or Siltstone

Arenite (if sandstone)

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Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

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Chert Breccia

Brecciated Chert (Microcrystalline Silica)

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Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

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Shale or Slaty Mudstone

Argillaceous sedimentary rock

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Sandstone

Arenite (primarily SiO2)

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