metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron Oxide inclusions)
Hardness: 6.5-7 (Mohs scale); Color: Golden to red-brown; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64-2.71
- Hardness
- 6
- Color
- Golden to red-brown
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Golden to red-brown; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64-2.71
Formation & geological history
Formed via the replacement of the fibrous blue mineral crocidolite (asbestos) by silica. This is a pseudomorphic process where quartz replaces the asbestos fibers while retaining their fibrous structure, resulting in chatoyancy. Most deposits are billions of years old, primarily found in iron-rich metamorphic formations.
Uses & applications
Primarily used as a gemstone in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for crystal collecting.
Geological facts
Historically, Roman soldiers wore Tiger's Eye for protection in battle. It is famous for the 'chatoyant' effect (the 'cat's eye' shimmer), which is caused by light reflecting off the internal parallel fibers. If the stone is naturally blue, it is called Hawk's Eye.
Field identification & locations
Identify in the field by its distinct golden-brown alternating bands and the way light seems to move across the surface (chatoyancy) when tilted. Major locations include South Africa (Northern Cape), Western Australia, India, and Namibia.
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