metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Golden yellow to brown, multi-toned; Luster: Silky; Crystal structure: Trigonal/Fibrous; Cleavage: None; Specific gravity: 2.64-2.71; Notable for its chatoyancy effect.
- Hardness
- 6
- Color
- Golden yellow to brown, multi-toned
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Golden yellow to brown, multi-toned; Luster: Silky; Crystal structure: Trigonal/Fibrous; Cleavage: None; Specific gravity: 2.64-2.71; Notable for its chatoyancy effect.
Formation & geological history
Formed when the mineral crocidolite is replaced by silica (quartz) while retaining the original fibrous structure. This metamorphic process creates a 'pseudomorph' where quartz takes on the shape of another mineral's fibers.
Uses & applications
Primarily used as a gemstone in jewelry, decorative carvings, and as a semi-precious stone for metaphysical collecting. It is also used in small industrial decorative accents.
Geological facts
Tiger's eye exhibits a unique optical effect called chatoyancy, which creates a vertical band of reflected light resembling a cat's eye. Ancient Roman soldiers wore it for protection in battle.
Field identification & locations
Identify in the field by its distinct golden-brown fibrous bands and the way the light shifts over the surface when rotated. Major deposits are found in South Africa, Western Australia, India, and Namibia.
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