metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron inclusions)
Hardness: 6.5–7 (Mohs scale); Color: Golden yellow, honey brown, reddish-brown, and blue; Luster: Silky to glassy; Crystal structure: Trigonal; Cleavage: None; Specific Gravity: 2.64–2.71; Notable for chatoyancy (cat's eye effect).
- Hardness
- 6
- Color
- Golden yellow, honey brown, reddish-brown, and blue
- Luster
- Silky to glassy
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Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Golden yellow, honey brown, reddish-brown, and blue; Luster: Silky to glassy; Crystal structure: Trigonal; Cleavage: None; Specific Gravity: 2.64–2.71; Notable for chatoyancy (cat's eye effect).
Formation & geological history
Formed through a pseudomorphic process where silica (quartz) replaces the fibrous mineral crocidolite (blue asbestos) over millions of years. The original fibrous structure is preserved while the asbestos is replaced by quartz. Most deposits are Proterozoic in age (approx. 2 billion years old).
Uses & applications
Predominantly used for jewelry (beads, cabochons), ornamental carvings, and as a popular stone for mineral collectors and metaphysical practitioners.
Geological facts
The reddish variety (natural or heat-treated) is known as 'Red Tiger's Eye' or 'Bull's Eye,' while the blue, unoxidized variety is called 'Hawk's Eye.' It was once considered as rare and precious as diamond until large deposits were found in South Africa.
Field identification & locations
Identify by its characteristic chatoyancy—the shifting band of light that moves across the surface as the stone is rotated under a light source. Commonly found in South Africa (Cape Province), Western Australia, India, and Myanmar.
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