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 silky chatoyancy; Luster: Silky to vitreous; Crystal structure: Trigonal/Fibrous; Cleavage: None; Specific gravity: 2.64–2.71
- Hardness
- 6
- Color
- Golden-yellow to deep brown with silky chatoyancy
- Luster
- Silky to vitreous
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Physical properties
Hardness: 6.5–7 on Mohs scale; Color: Golden-yellow to deep brown with silky chatoyancy; Luster: Silky to vitreous; 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. As quartz replaces the fibrous mineral, it retains the hair-like structure, while iron oxidation creates the gold and brown hues. Most deposits are found in Precambrian rock formations.
Uses & applications
Primarily used in jewelry (cabochons and beads), ornamental carvings, and 'metaphysical' collecting. Its durability also makes it popular for inlay work and small sculptures.
Geological facts
It is a 'pseudomorph,' meaning 'false form,' because it is quartz taking the physical shape of a different mineral. Roman soldiers used to wear it for protection in battle due to its 'all-seeing eye' appearance.
Field identification & locations
Identify in the field by its distinct chatoyancy (the 'cat’s eye' effect) when rotated under light and its golden-brown banding. Key locations include South Africa, Western Australia, Namibia, and India.
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