sedimentary
Mookaite Jasper
Mookaite (Silicified radiolarite, SiO2)
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
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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.
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