metamorphic
Tiger's Eye (Nodule/Tumbled)
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron inclusions)
Hardness: 7 (Mohs), Color: Golden brown to brownish-black with chatoyancy, Luster: Silky, Structure: Hexagonal (Trigonal), Cleavage: None, Specific Gravity: 2.64-2.71
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Physical properties
Hardness: 7 (Mohs), Color: Golden brown to brownish-black with chatoyancy, Luster: Silky, Structure: Hexagonal (Trigonal), Cleavage: None, Specific Gravity: 2.64-2.71
Formation & geological history
Formed through the replacement of fibrous crocidolite asbestos by silica (quartz) over millions of years. This process is a pseudomorphism. Most deposits are found in Precambrian banded iron formations.
Uses & applications
Predominantly used for lapidary work including jewelry (cabochons, beads), decorative carvings, and as a popular 'protection' stone in spiritual communities.
Geological facts
Tiger's eye exhibits a unique optical effect known as chatoyancy, or 'the cat's eye effect', caused by the parallel orientation of mineral fibers. If the stone is predominantly blue, it is known as Hawk's Eye.
Field identification & locations
Identify by the silky luster and moving bands of light (chatoyancy) when the stone is rotated under light. Major locations include South Africa (Northern Cape province), Western Australia, India, and Namibia.
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