metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
Hardness: 6.5–7 (Mohs scale); Color: Golden to red-brown; Luster: Silky; Crystal Structure: Hexagonal/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 (Mohs scale); Color: Golden to red-brown; Luster: Silky; Crystal Structure: Hexagonal/Trigonal (fibrous aggregate); Cleavage: None; Specific Gravity: 2.64–2.71
Formation & geological history
Formed when quartz replaces the fibrous mineral crocidolite (blue asbestos) through a process of pseudomorphism within metamorphic rock formations, primarily during the Precambrian era.
Uses & applications
Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal collecting and metaphysical purposes.
Geological facts
It exhibits a unique optical effect known as chatoyancy (the 'cat's eye' effect). When the crocidolite is replaced by quartz but retains its fibrous structure, iron becomes oxidized to create the distinctive golden-yellow and brown colors.
Field identification & locations
Identify by its characteristic 'shimmer' or moving band of light when rotated under a light source. Commonly found in South Africa, Western Australia, India, and Burma. Collectors should look for vibrant banding and a high-polish finish.
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