metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
Hardness: 6.5-7 (Mohs); Color: Golden to red-brown stripes; Luster: Silky; Crystal structure: Trigonal/Fibrous; Specific gravity: 2.64-2.71
- Hardness
- 6
- Color
- Golden to red-brown stripes
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Golden to red-brown stripes; Luster: Silky; Crystal structure: Trigonal/Fibrous; Specific gravity: 2.64-2.71
Formation & geological history
Formed through a metamorphic process known as pseudomorphism where quartz replaces the fibrous mineral crocidolite (blue asbestos) while retaining its fibrous structure. Significant deposits are found in Precambrian rock formations.
Uses & applications
Extensively used in jewelry (cabochons, beads), decorative carvings, and as a popular collector's gemstone for its chatoyancy.
Geological facts
The optical effect is called chatoyancy (cat's eye effect). Roman soldiers were known to carry it for protection in battle. It is primarily sourced from South Africa and Western Australia.
Field identification & locations
Identify by the distinct gold and brown parallel bands that shift luster when rotated under light. Commonly found in iron formations. Tips: ensure the 'shifting' light effect is present to distinguish from jasper.
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