metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5–7 (Mohs); Color: Golden brown to yellowish-brown with silky bands; Luster: Silky; Crystal system: Trigonal/Hexagonal; Cleavage: None; Specific Gravity: 2.64–2.71; Notable for chatoyancy (cat's eye effect).
- Hardness
- 6
- Color
- Golden brown to yellowish-brown with silky bands
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 (Mohs); Color: Golden brown to yellowish-brown with silky bands; Luster: Silky; Crystal system: Trigonal/Hexagonal; Cleavage: None; Specific Gravity: 2.64–2.71; Notable for chatoyancy (cat's eye effect).
Formation & geological history
Formed through the metamorphic process known as pseudomorphism, where silica-rich fluids replace the fibrous blue asbestos mineral (crocidolite) while maintaining its fibrous structure. Often found in Precambrian iron formations.
Uses & applications
Primarily used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal healing and mineral collectors.
Geological facts
It is a member of the quartz family and exhibits a unique optical effect called chatoyancy. When the fibers are replaced by quartz but the iron is not oxidized, it remains blue and is called 'Hawk\'s Eye'.
Field identification & locations
Identify by its distinctive golden-brown shifting bands when rotated under light. Major deposits are in South Africa, Western Australia, India, and Myanmar. Common in rock shops; look for the 'silky' fibers under the surface.
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