metamorphic
Tiger's Eye (Blue-Gold transition)
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5–7 Mohs; Color: Bands of golden-brown, blue-grey, and black; Luster: Silky to vitreous; Crystal structure: Trigonal/Fibrous; Chatoyancy (cat's eye effect); Specific Gravity: 2.64–2.71
- Hardness
- 6
- Color
- Bands of golden-brown, blue-grey, and black
- Luster
- Silky to vitreous
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Physical properties
Hardness: 6.5–7 Mohs; Color: Bands of golden-brown, blue-grey, and black; Luster: Silky to vitreous; Crystal structure: Trigonal/Fibrous; Chatoyancy (cat's eye effect); Specific Gravity: 2.64–2.71
Formation & geological history
Formed through the replacement of fibrous blue asbestos (crocidolite) with silica (quartz) over geological time, creating a pseudomorph. Heating and iron oxidation turn the blue 'Hawks Eye' into the golden 'Tiger's Eye'. Found in metamorphosed iron formations.
Uses & applications
Predominantly used for jewelry (cabochons, beads), decorative carvings, spiritual/metaphysical collecting, and lapidary arts.
Geological facts
The shimmering effect is called chatoyancy. When the specimen contains both gold and blue fibers, it is often called 'Zebra Tiger's Eye'. It is a classic example of a 'pseudomorph' where one mineral replaces another while retaining the original's shape.
Field identification & locations
Identify by rotating under light to observe the moving golden bands (chatoyancy). Commonly found in South Africa (Griquatown) and Western Australia. Collectors look for sharp, distinct banding and high luster.
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