metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with iron oxide inclusions)
Hardness: 6.5–7; Color: Golden-yellow to honey-brown; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64–2.71.
- Hardness
- 6
- Color
- Golden-yellow to honey-brown
- Luster
- Silky
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Physical properties
Hardness: 6.5–7; Color: Golden-yellow to honey-brown; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64–2.71.
Formation & geological history
Formed through a metamorphic process known as pseudomorphism where quartz replaces the fibrous mineral crocidolite (blue asbestos). It typically occurs in banded iron formations through low-grade metamorphism.
Uses & applications
Predominantly used for lapidary purposes including beads, cabochons, carvings, and as a popular semi-precious gemstone in jewelry. It is also a common specimen for crystal collecting.
Geological facts
Tiger's Eye exhibits an optical effect called chatoyancy (cat's eye effect) due to the parallel intergrowth of quartz crystals and altered amphibole fibers. If the iron is oxidized to a lesser degree, it becomes Hawk's Eye (blue).
Field identification & locations
Identify by its characteristic golden-brown bands and silky shimmer when tilted under light. Commonly found in South Africa, Western Australia, Myanmar, and Namibia. Collectors should look for distinct banding and high luster.
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