mineral

Blue Tiger's Eye

Silicified Riebeckite (SiO2)

Hardness: 6.5-7 Mohs; Color: Blue-gray to dark blue with golden or brown bands; Luster: Silky; Crystal Structure: Trigonal (fibrous); Cleavage: None; Specific Gravity: 2.64-2.71

Hardness: 6
Color: Blue-gray to dark blue with golden or brown bands
Luster: Silky

Identified June 12, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Blue-gray to dark blue with golden or brown bands; Luster: Silky; Crystal Structure: Trigonal (fibrous); Cleavage: None; Specific Gravity: 2.64-2.71

Formation & geological history

Formed through the pseudomorphism of crocidolite fibers by quartz. This metamorphic process replaces the original asbestos mineral while preserving the fibrous structure, creating chatoyancy.

Uses & applications

Primarily used in jewelry for cabochons and beads, as well as for ornamental carvings and lapidary art. It is also a popular specimen for crystal collecting.

Geological facts

Also known as 'Hawks Eye', it is often the precursor to the more common golden-yellow Tiger's Eye. If the iron within the fibers has not been oxidized, it remains blue.

Field identification & locations

Identified by its characteristic chatoyancy (the 'cat's eye' effect) and moving bands of light. Commonly found in South Africa and Western Australia. Collectors should look for a smooth, silky luster and strong light-reflecting bands.