sedimentary

Mookaite Jasper

Mookaite (Silicified radiolarite, SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Striated bands of red, yellow, cream, and ochre; Luster: Vitreous to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Conchoidal fracture.

Hardness: 6
Color: Striated bands of red, yellow, cream, and ochre
Luster: Vitreous to dull

Identified July 5, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Striated bands of red, yellow, cream, and ochre; Luster: Vitreous to dull; Crystal structure: Microcrystalline/Cryptocrystalline; Conchoidal fracture.

Formation & geological history

Formed during the Cretaceous Period (approx. 66-145 million years ago) through the silicification of radiolaria (microscopic marine organisms) in shallow, near-shore environments.

Uses & applications

Primarily used as a semi-precious gemstone in jewelry, lapidary arts for cabochons and carvings, and as a popular collector's specimen.

Geological facts

Named after Mooka Creek in Western Australia, which is the only place in the world where this specific type of radiolarite is found. The word 'Mooka' means 'running waters' in the local Aboriginal language.

Field identification & locations

Identified by its distinctive 'swirled' color patterns and high silica content that gives it a flint-like feel. Collectors should look for vibrant, opaque colors without large cracks. Found exclusively in the Windalia Radiolarite formation.