metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5-7 Mohs; Color: Golden yellow to brown with chatoyant bands; Luster: Silky; Crystal structure: Trigonal (fibrous); Cleavage: None; Specific Gravity: 2.64-2.71
- Hardness
- 6
- Color
- Golden yellow to brown with chatoyant bands
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 Mohs; Color: Golden yellow to brown with chatoyant bands; Luster: Silky; Crystal structure: Trigonal (fibrous); Cleavage: None; Specific Gravity: 2.64-2.71
Formation & geological history
Formed through the pseudomorphism of crocidolite (blue asbestos) fiber by silica. As quartz replaces the fibers, it retains the fibrous structure, creating chatoyancy. Most deposits are found in Precambrian banded iron formations.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative carvings, and as a popular collector's specimen due to its unique optical properties.
Geological facts
The 'eye' effect is known as chatoyancy. It is believed by some cultures to provide protection and clarity. It is the anniversary gemstone for the 9th year of marriage.
Field identification & locations
Identify by moving the stone under a light source to observe the shifting 'cat-eye' bands. Commonly found in South Africa (Northern Cape), Australia, and Namibia. Collectors look for high luster and straight, sharp banding.
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