metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
Hardness: 6.5–7 on Mohs scale; Color: Golden yellow to deep brown with banding; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64–2.71
- Hardness
- 6
- Color
- Golden yellow to deep brown with banding
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Golden yellow to deep brown with banding; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64–2.71
Formation & geological history
Formed through a metamorphic process called pseudomorphism, where silica (Quartz) replaces the original fibrous mineral Crocidolite (blue asbestos). The golden color comes from the oxidation of iron within the structure during replacement. Major deposits are found in Precambrian rock formations.
Uses & applications
Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and metaphysical collecting. In historical industry, it was used for small tool handles or ornamental inlay.
Geological facts
It exhibits a unique optical effect known as chatoyancy, or the 'cat's eye' effect, caused by the reflection of light off the parallel fibrous internal structure. Roman soldiers were known to carry it to protect them in battle.
Field identification & locations
Identify by its distinctive golden-brown vertical banding and the shimmering effect (chatoyancy) when tilted. It is most commonly found in South Africa (Griquatown West), Western Australia, India, and Myanmar. For collectors, look for high-contrast banding and 'silk' luster.
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