sedimentary

Chert (Mookaite Jasper style)

Microcrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs), Color: variegated reddish-brown, tan, mustard yellow, and cream. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6-2.7.

Hardness: 6
Color: variegated reddish-brown, tan, mustard yellow, and cream
Luster: Vitreous to waxy

Identified June 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via the accumulation of silica-rich skeletal remains of radiolarians or the replacement of limestone. This specific multicolored variety is often associated with the Mooka Creek region of Australia, formed during the Cretaceous period in a shallow sea environment.

Uses & applications

Used primarily in lapidary work for jewelry, cabochons, and decorative carvings. Historically used for stone tools and projectile points due to its sharp edges.

Geological facts

Mookaite is named after Mooka Creek in Western Australia. The term 'Jasper' is technically the opaque variety of chert. It is famous for its vibrant earthy tones caused by iron oxides and hydroxides.

Field identification & locations

Identify by its smooth, waxy texture and shell-like (conchoidal) fracture when broken. It cannot be scratched by a steel knife. Common in Australia but varied chert is found globally in sedimentary basins.

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Sandstone Grain

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