metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5-7 Mohs. Color: Golden to red-brown with silky luster. Structure: Trigonal. Features strong chatoyancy (cat's eye effect) and no cleavage.
- Hardness
- 6
- Color
- Golden to red-brown with silky luster
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Physical properties
Hardness: 6.5-7 Mohs. Color: Golden to red-brown with silky luster. Structure: Trigonal. Features strong chatoyancy (cat's eye effect) and no cleavage.
Formation & geological history
Formed when quartz replaces fibrous crocidolite (blue asbestos) through a pseudomorphic process. The iron in the fibers oxidizes, creating the golden brown color. Primarily found in Precambrian banded iron formations.
Uses & applications
Extensively used in jewelry (cabochons, beads), decorative carvings, and as a popular collected tumbled stone.
Geological facts
It is a classic example of chatoyancy. It was once considered rare and highly valuable in the 1800s until major deposits were found in South Africa.
Field identification & locations
Identify by its distinctive silky golden stripes that shift in the light. In the field, look for fibrous textures in ironstone. Largest deposits are found in Northern Cape, South Africa and Western Australia.
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