mineral
Tiger's Eye / Hawk's Eye
Pseudomorph of Quartz after Crocidolite (SiO2)
AI-generated identification · may be incorrectHardness: 6.5-7 on Mohs scale; Color: Blue-grey (Hawk's Eye) and Golden-brown (Tiger's Eye); Luster: Silky; Crystal Structure: Trigonal (fibrous aggregate); Cleavage: None; Specific Gravity: 2.64-2.71.
- Hardness
- 6
- Color
- Blue-grey (Hawk's Eye) and Golden-brown (Tiger's Eye)
- Luster
- Silky
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Physical properties
Hardness: 6.5-7 on Mohs scale; Color: Blue-grey (Hawk's Eye) and Golden-brown (Tiger's Eye); Luster: Silky; Crystal Structure: Trigonal (fibrous aggregate); Cleavage: None; Specific Gravity: 2.64-2.71.
Formation & geological history
Formed through a pseudomorphic process where silica (quartz) replaces the fibrous mineral crocidolite. It typically forms in metamorphic environments within iron formations. This specific piece shows a transition between Blue Hawk's Eye and Golden Tiger's Eye.
Uses & applications
Widely used in jewelry making (cabochons, beads), decorative carvings, and as a popular collector's stone due to its chatoyancy.
Geological facts
It exhibits 'chatoyancy', a cat-eye effect caused by the reflection of light off the parallel fibrous structure. The golden color in Tiger's Eye is caused by the oxidation of iron within the crocidolite fibers, whereas blue Hawk's Eye remains unoxidized.
Field identification & locations
Identified in the field by its distinct parallel bands and shifting 'silk' luster when tilted. Major sources include South Africa, Australia, Burma, and Namibia. Collectors value pieces with sharp bands and mixed colors.
