metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite
Hardness: 6.5-7.0 (Mohs scale); Color: Golden to reddish-brown; Luster: Silky; Crystal structure: Trigonal (fibrous); Cleavage: None; Specific Gravity: 2.64-2.71.
- Hardness
- 6
- Color
- Golden to reddish-brown
- Luster
- Silky
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Physical properties
Hardness: 6.5-7.0 (Mohs scale); Color: Golden to reddish-brown; Luster: Silky; Crystal structure: Trigonal (fibrous); Cleavage: None; Specific Gravity: 2.64-2.71.
Formation & geological history
Formed when quartz replaces the mineral crocidolite (blue asbestos) through a process called pseudomorphism, retaining the fibrous structure. It typically originates in iron-bearing metamorphic rocks.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative carvings, and as a popular collector's gemstone due to its chatoyancy.
Geological facts
Tiger's Eye displays a unique optical effect known as chatoyancy or the 'cat-eye effect,' caused by the reflection of light off the internal fibrous structure. If it is heat-treated, it turns red and is called 'Bull\'s Eye.'
Field identification & locations
Identify by its characteristic golden-brown bands and silky, shimmering effect when moved under light. Major deposits are found in South Africa, Western Australia, and India.
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