metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron inclusions)
Hardness: 6.5–7 on Mohs scale; Color: Golden to red-brown; Luster: Silky; Crystal Structure: Trigonal (fibrous aggregate); Cleavage: None; Specific Gravity: 2.64–2.71.
- Hardness
- 6
- Color
- Golden to red-brown
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Golden to red-brown; Luster: Silky; Crystal Structure: Trigonal (fibrous aggregate); Cleavage: None; Specific Gravity: 2.64–2.71.
Formation & geological history
Formed through the pseudomorphism of crocidolite (blue asbestos) crystals by quartz. The iron in the original crocidolite oxidizes to create the golden-brown color. Most deposits are Proterozoic in age (approx. 2 billion years old).
Uses & applications
Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for mineral collectors due to its unique optical properties.
Geological facts
It exhibits a unique optical effect known as chatoyancy (the 'cat's eye' effect), where a band of light moves across the stone as it is rotated. It is often found near 'Hawk's Eye' (the blue, unoxidized version).
Field identification & locations
Identify in the field by its distinct golden-yellow and brown bands and its silky luster. It is most commonly found in South Africa (Northern Cape), Western Australia, and Namibia. Collectors look for high luster and sharp chatoyant bands.
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