Rock Identifier
Blue Tiger's Eye (Crocidolite in Quartz (altered)) — Mineral
Mineral

Blue Tiger's Eye

Crocidolite in Quartz (altered)

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Deep blue to grayish-blue, often with bands or streaks of darker and lighter shades. Luster: Silky or vitreous. Crystal Structure: Trigonal (quartz). exhibits chatoyancy, a silky, luminous streak which appears to move as the stone is rotated, due to the fibrous crocidolite inclusio…

Hardness
6
Luster
Silky or vitreous
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Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Deep blue to grayish-blue, often with bands or streaks of darker and lighter shades. Luster: Silky or vitreous. Crystal Structure: Trigonal (quartz). exhibits chatoyancy, a silky, luminous streak which appears to move as the stone is rotated, due to the fibrous crocidolite inclusions. Opaque.

Formation & geological history

Blue Tiger's Eye forms when blue crocidolite asbestos fibers are replaced by quartz, while maintaining their fibrous structure. This pseudomorphosis results in the characteristic chatoyancy. It typically forms in metamorphic rock environments where hydrothermal solutions interact with iron-rich precursor rocks. Geological Age: Varies, often associated with Precambrian formations.

Uses & applications

Primarily used as a gemstone in jewelry, especially for beads, cabochons, and ornamental carvings, due to its distinctive optical effect. Also valued by collectors of minerals and unique gemstones.

Geological facts

Blue Tiger's Eye is also known as Hawk's Eye. It is closely related to golden Tiger's Eye and red Tiger's Eye, with the color variation depending on the oxidation state of iron within the crocidolite fibers. Blue Tiger's Eye is less oxidized than golden Tiger's Eye.

Field identification & locations

In the field, look for its distinctive blue color and the chatoyant effect (cat's eye effect) when light reflects off its surface. Common locations include South Africa, India, and parts of Australia. Collectors can identify it by its specific color and chatoyancy, which differentiates it from other fibrous minerals or blue gemstones. It is often found in massive form rather than distinct crystal habits.

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