metamorphic
Tiger's Eye
Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions)
Hardness: 6.5-7 (Mohs); Color: Golden to red-brown; Luster: Silky; Crystal structure: Trigonal/Fibrous; Specific Gravity: 2.64-2.71; Notable for chatoyancy (cat's eye effect).
- Hardness
- 6
- Color
- Golden to red-brown
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Golden to red-brown; Luster: Silky; Crystal structure: Trigonal/Fibrous; Specific Gravity: 2.64-2.71; Notable for chatoyancy (cat's eye effect).
Formation & geological history
Formed when quartz replaces fibrous crocidolite (blue asbestos) via a process called pseudomorphism, resulting in a chatoyant gemstone. Commonly found in iron formations.
Uses & applications
Used extensively in jewelry (cabochons, beads), decorative carvings, clock faces, and as a popular collector's mineral.
Geological facts
The 'eye' effect is created by the parallel arrangement of quartz fibers and altered amphibole fibers. A blue variety exists known as Hawk's Eye.
Field identification & locations
Identify by the silky luster and moving band of light when rotated. Predominantly sourced from the Northern Cape Province in South Africa and the Pilbara region of Western Australia.
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