metamorphic
Tiger's Eye
Pseudomorph of quartz after crocidolite (SiO2)
Hardness: 6.5–7 (Mohs); Color: Golden yellow to deep brown with darker bands; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific Gravity: 2.64–2.71.
- Hardness
- 6
- Color
- Golden yellow to deep brown with darker bands
- Luster
- Silky
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Physical properties
Hardness: 6.5–7 (Mohs); Color: Golden yellow to deep brown with darker bands; Luster: Silky; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific Gravity: 2.64–2.71.
Formation & geological history
Formed through a metamorphic process where quartz replaces the fibers of the mineral crocidolite (asbestiform riebeckite) while preserving the original fibrous structure. This is known as pseudomorphism. Common in Precambrian aged iron formations.
Uses & applications
Primarily used as a gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for collectors due to its chatoyancy.
Geological facts
The 'shimmer' effect is known as chatoyancy, similar to a cat's eye. Historically, Tiger's Eye was considered a stone of protection and good luck in various ancient cultures, including Roman soldiers who wore it into battle.
Field identification & locations
Identify in the field by its distinct silky luster and the 'moving' bands of light (chatoyancy) when the stone is tilted. It is most commonly found in South Africa (Northern Cape), Australia, Myanmar, and India.
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