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 with silky luster; Chatoyancy: Distinctive 'cat's eye' effect; Structure: Fibrous/Trigonal; SG: 2.64-2.71
- Hardness
- 6
- Color
- Golden to red-brown with silky luster
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Golden to red-brown with silky luster; Chatoyancy: Distinctive 'cat's eye' effect; Structure: Fibrous/Trigonal; SG: 2.64-2.71
Formation & geological history
Formed as a metamorphic pseudomorph. It begins as fibrous blue asbestos (crocidolite) which is replaced by quartz while retaining the fibrous structure. Iron within the stone oxidizes to create the golden-brown hues.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative lapidary carvings, and as a popular specimen for rock collectors and metaphysical enthusiasts.
Geological facts
It is famous for the 'optical illusion' of chatoyancy, where light reflects off the fibrous inclusions to create a moving band of light. Ancient Romans carried it to protect them in battle.
Field identification & locations
Identify in the field by its distinct golden-brown banding and silky reflection when tilted. Major locations include South Africa (Grientaland West), Australia, India, and Namibia.
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