metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5-7 Mohs; Color: Golden-brown to yellow with dark stripes; Luster: Silky; Crystal structure: Trigonal (fibrous); Specific gravity: 2.64-2.71; Chatoyancy (cat's eye effect)
- Hardness
- 6
- Color
- Golden-brown to yellow with dark stripes
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 Mohs; Color: Golden-brown to yellow with dark stripes; Luster: Silky; Crystal structure: Trigonal (fibrous); Specific gravity: 2.64-2.71; Chatoyancy (cat's eye effect)
Formation & geological history
Formed through the pseudomorphism of crocidolite asbestos by silica. Iron oxides provide the golden coloration. Commonly found in banded iron formations.
Uses & applications
Primarily used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular collector's specimen.
Geological facts
The 'eye' effect is known as chatoyancy, which is caused by the reflection of light from the parallel fibrous structure within the stone. If it is blue, it is called Hawk's Eye.
Field identification & locations
Identified by its distinctive gold and brown stripes and silky chatoyancy. Major deposits are found in South Africa and Western Australia. Use the 'scratch test' (quartz hardness) and look for shifting light bands.
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