metamorphic
Tiger's Eye
Silicon dioxide (SiO2) with fibrous inclusions of Crocidolite (Asbestos) replaced by Quartz
Hardness: 6.5–7 Mohs; Color: Golden yellow to silky brown; Luster: Silky; Crystal structure: Trigonal (fibrous); Cleavage: None; Chatoyancy (cat-eye effect) is its most distinct property.
- Hardness
- 6
- Color
- Golden yellow to silky brown
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 Mohs; Color: Golden yellow to silky brown; Luster: Silky; Crystal structure: Trigonal (fibrous); Cleavage: None; Chatoyancy (cat-eye effect) is its most distinct property.
Formation & geological history
Formed through the pseudomorphism of crocidolite (blue asbestos) by silica. The iron within the original fibers oxidizes to a golden-brown color during the process. Major deposits date to the Precambrian era.
Uses & applications
Primarily used as a semi-precious gemstone in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal collectors.
Geological facts
Tiger's Eye is known for its chatoyancy, an optical effect where light reflects off the parallel fibrous inclusions to create a band of light across the surface. It is considered a 'pseudomorph' because quartz takes the shape of the original mineral.
Field identification & locations
Identify by its distinct golden-brown horizontal banding and silky luster that 'moves' when the stone is tilted. It is most commonly found in South Africa (Northern Cape Province) and Western Australia.
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