metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (Silicon Dioxide: SiO2)
Hardness: 6.5-7 (Mohs). Color: Golden yellow to deep brown with silky chatoyant bands. Luster: Silky. Crystal structure: Trigonal/Fibrous. Cleavage: None. Specific gravity: 2.64-2.71.
- Hardness
- 6
- Color
- Golden yellow to deep brown with silky chatoyant bands
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 (Mohs). Color: Golden yellow to deep brown with silky chatoyant bands. Luster: Silky. Crystal structure: Trigonal/Fibrous. Cleavage: None. Specific gravity: 2.64-2.71.
Formation & geological history
Formed through a metamorphic process known as pseudomorphism, where silica replaces fibrous crocidolite (asbestos) while maintaining the original fibrous structure. Most deposits are found in Precambrian iron formations.
Uses & applications
Primarily used in jewelry (beads, cabochons), ornamental carvings, and as a popular semi-precious stone for collectors emphasizing its chatoyancy.
Geological facts
The unique 'shimmer' is called chatoyancy or the 'cat-eye effect.' Historically, it was worn by Roman soldiers in battle for protection and was once valued more highly than gold before large deposits were found in South Africa.
Field identification & locations
Identify in the field by its distinct golden-brown bands that seem to move when the stone is rotated under a light source. Commonly found in South Africa, Australia, Burma, and India. Look for silky luster and fibrous texture in raw specimens.
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