sedimentary

Mookaite Jasper

Silicified Radiolarite (Silicon Dioxide: SiO2)

Hardness: 6.5-7 (Mohs scale); Color: Variegated red, yellow, cream, and brown; Luster: Vitreous to dull; Crystal Structure: Microcrystalline/Cryptocrystalline; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.6-2.7

Hardness: 6
Color: Variegated red, yellow, cream, and brown
Luster: Vitreous to dull

Identified March 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed during the Cretaceous period (approx. 145-66 million years ago) through the silicification of radiolarite skeletal remains in a shallow sea environment. The silica from these organisms replaced original materials to create a dense, chert-like rock.

Uses & applications

Primary use is in jewelry (cabochons, beads) and ornamental carvings. It is popular among mineral collectors and used as a pocket stone or decorative tumble. Historically used by indigenous populations for tool production.

Geological facts

Mookaite is found exclusively in the Kennedy Ranges of Western Australia, specifically near Mooka Creek, from which it takes its name. The word 'Mooka' means 'running waters' in the local Aboriginal language.

Field identification & locations

Identify by its distinctive pastel to earthy color palette and high polish. In the field, look for nodules or beds in dry creek beds of the Kennedy Range. It is opaque, hard enough to scratch glass, and often shows 'brecciated' or swirled patterns.

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