sedimentary

Mookaite Jasper

Radiolarite (Silicified radiolarian chert)

Hardness: 6.5-7 on Mohs scale; Color: Red, purple, mustard yellow, cream, and maroon; Luster: Vitreous to dull (polished in photo); Crystal Structure: Hexagonal (cryptocrystalline); Cleavage: None, conchoidal fracture

Hardness: 6
Color: Red, purple, mustard yellow, cream, and maroon
Luster: Vitreous to dull (polished in photo)

Identified June 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as a sedimentary deposit of radiolarian remains (microscopic sea creatures) that were silicified by silica-rich groundwater. Found specifically in the Mooka Creek area of Western Australia, dating to the Cretaceous period (approx. 145-66 million years ago).

Uses & applications

Primarily used as a semi-precious gemstone for jewelry, lapidary work, cabochons, carvings, and as a popular specimen for mineral collectors.

Geological facts

The name 'Mooka' comes from the Aboriginal word meaning 'running waters'. It is unique because it combines the characteristics of both jasper and opalite in its geological formation.

Field identification & locations

Identify by its distinctive earthy color palette and porcelaneous texture. Found almost exclusively in the Windalia Radiolarite formation in Western Australia. Collectors look for vibrant, contrasting color bands.

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Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

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)

sedimentary