metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of iron oxide)
Hardness: 6.5-7 (Mohs scale); Color: Golden to red-brown; Luster: Silky; Crystal Structure: Trigonal/Fibrous; 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; Cleavage: None; Specific Gravity: 2.64-2.71
Formation & geological history
Formed through the pseudomorphism of blue asbestos (crocidolite). Over time, silica (quartz) replaces the asbestos fibers while maintaining their fibrous structure, often becoming oxidized by iron to create the golden-brown color.
Uses & applications
Predominantly used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for rock and mineral collectors due to its unique optical properties.
Geological facts
Exhibits a distinct optical phenomenon called 'chatoyancy' (cat-eye effect). When moved under light, the fibers create a shimmering band of light. It was historically believed to provide protection and mental clarity to the wearer.
Field identification & locations
Identify in the field by its distinct parallel fibrous bands and golden-brown luster. It is highly abundant in South Africa (Northern Cape Province), Western Australia, India, and Burma. Collectors look for high chatoyancy and few surface pits.
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