sedimentary

Mookaite Jasper

Silicified Radiolarite (SiO2)

Hardness: 6.5–7 (Mohs scale); Color: Variegated shades of mustard yellow, maroon, cream, brick red, and purple; Luster: Vitreous to greasy; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.63 - 2.65.

Hardness: 6
Luster: Vitreous to greasy

Identified March 23, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as a sedimentary rock composed of the skeletal remains of radiolaria (microscopic marine organisms). These remains settled in shallow seabed environments, then underwent silicification (replacement of organic material with silica) over millions of years, primarily during the Cretaceous period (roughly 145–66 million years ago).

Uses & applications

Used primarily in lapidary arts for jewelry (beads, cabochons, pendants), ornamental carvings, and as a popular specimen for crystal and mineral collectors.

Geological facts

Mookaite is found specifically in the Kennedy Ranges of Western Australia near Mooka Creek. The name 'Mooka' is an Aboriginal word meaning 'running waters.' It is unique because it is technically a fossilized siltstone that has been chemically altered into jasper.

Field identification & locations

Identification in the field is based on its distinct earthy color palette and porcelain-like texture when broken. It is an Australian 'heritage' stone. Collectors look for high-contrast patterns and rare colors like vivid purple or pink within the stone.