metamorphic
Tiger's Eye
Silicon dioxide (SiO2) with inclusions of Limonite
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
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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 through the pseudomorphism of crocidolite (blue asbestos) by quartz. The asbestos fibers are replaced by silica while maintaining the fibrous structure, creating chatoyancy. Most deposits are found in banded iron formations of Precambrian age.
Uses & applications
Mainly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular collector's mineral.
Geological facts
The characteristic silky luster, known as chatoyancy or the 'cat\'s eye effect', is caused by light reflecting off the internal fibrous structure. Unlike many other gemstones, its beauty is enhanced by movement.
Field identification & locations
Identify by its golden-brown bands and the shimmer (chatoyancy) that moves when the stone is tilted. It is commonly found in South Africa, Western Australia, and India. Look for parallel fibrous layering in the field.
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