Rock Identifier
Zebra Rock (Zebra Stone / Ribbon Stone) (Siltstone with Ferruginous Banding (Primarily Quartz, Kaolinite, and Hematite)) — sedimentary
sedimentary

Zebra Rock (Zebra Stone / Ribbon Stone)

Siltstone with Ferruginous Banding (Primarily Quartz, Kaolinite, and Hematite)

Hardness: 6.5 - 7 (Mohs scale); Color: Dark brown or black base with white, tan, or grey stripes; Luster: Dull to earthy; Crystal structure: Microcrystalline/non-crystalline; Cleavage: None/Conchoidal fracture.

Hardness
6
Color
Dark brown or black base with white, tan, or grey stripes
Luster
Dull to earthy
Identified More sedimentary

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Physical properties

Hardness: 6.5 - 7 (Mohs scale); Color: Dark brown or black base with white, tan, or grey stripes; Luster: Dull to earthy; Crystal structure: Microcrystalline/non-crystalline; Cleavage: None/Conchoidal fracture.

Formation & geological history

Formed through the rhythmic precipitation of iron oxide (hematite) within a fine-grained clay or siltstone matrix. Primarily found in the Ranford Formation, dating back to the Proterozoic era (approximately 600 million years ago).

Uses & applications

Used in the creation of unique jewelry (cabochons), ornamental carvings, figurines, and interior decorative items like vases and bookends.

Geological facts

The exact biological or environmental triggers for the perfectly spaced 'zebra' stripes remain a geological mystery, though some scientists theorize they are a result of Liesegang banding or fossilized microbial mats.

Field identification & locations

Identify by its distinctive high-contrast parallel or concentric banding. It is famous for being found in the East Kimberley region of Western Australia. Collectors should look for sharp color boundaries without blurring.