metamorphic
Tiger's Eye
Pseudomorph of Chalcedony (SiO2) after Crocidolite
Hardness: 6.5–7 (Mohs); Color: Golden-yellow, brown, reddish; Luster: Silky; Crystal structure: Trigonal (fibrous aggregate); Cleavage: None; Specific gravity: 2.64–2.71.
- Hardness
- 6
- Color
- Golden-yellow, brown, reddish
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 (Mohs); Color: Golden-yellow, brown, reddish; Luster: Silky; Crystal structure: Trigonal (fibrous aggregate); Cleavage: None; Specific gravity: 2.64–2.71.
Formation & geological history
Formed through a metamorphic process known as pseudomorphism, where silica replaces fibrous crocidolite (asbestos) while maintaining its structure. Most deposits are approximately 2 billion years old.
Uses & applications
Predominantly used as a gemstone in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for collectors due to its unique optical properties.
Geological facts
It exhibits chatoyancy (the 'cat's eye' effect). When cut and polished, the light reflects off the fibrous internal structure, creating a band of light that moves as the stone is turned. It is considered a protective stone in various cultures.
Field identification & locations
Identified in the field by its distinct yellow-and-brown banding and silky luster. Most significant deposits are in South Africa (Northern Cape Province), Australia, and Thailand. Collectors look for high chatoyancy and few surface pits.
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