metamorphic
Tiger's Eye (Tumbled Blue/Black-Golden variety)
Pseudomorph of Quartz after Crocidolite (SiO2 with Iron inclusions)
Hardness: 7 Mohs; Color: Chatoyant bands of dark blue/black and golden-brown; Luster: Silky to vitreous; Crystal Structure: Hexagonal/Trigonal; Specific Gravity: 2.64-2.71.
- Hardness
- 7 Mohs
- Color
- Chatoyant bands of dark blue/black and golden-brown
- Luster
- Silky to vitreous
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Physical properties
Hardness: 7 Mohs; Color: Chatoyant bands of dark blue/black and golden-brown; Luster: Silky to vitreous; Crystal Structure: Hexagonal/Trigonal; Specific Gravity: 2.64-2.71.
Formation & geological history
Formed when quartz replaces fibrous crocidolite (blue asbestos) crystals while maintaining the fibrous structure. The golden color results from the oxidation of iron within the minerals.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative carvings, and as a popular collector's pocket stone.
Geological facts
It is a prime example of a pseudomorph. When the color remains blue, it is known as Hawk's Eye; when oxidized to gold/brown, it is Tiger's Eye. This specimen shows a transition between the two.
Field identification & locations
Identify by its unique 'chatoyancy' (cat's eye effect) where the light reflects off the fibrous bands as you rotate the stone. Commonly found in South Africa and Western Australia.
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