mineral

Blue Tiger's Eye

Pseudomorph of Quartz after Crocidolite (SiO2 with inclusions of asbestiform silicates)

Hardness: 6.5-7 (Mohs scale); Color: Dark blue, blue-gray, to black with silky bands; Luster: Silky to vitreous; Crystal structure: Trigonal (fibrous texture); Cleavage: None; Specific gravity: 2.64-2.71

Hardness: 6
Color: Dark blue, blue-gray, to black with silky bands
Luster: Silky to vitreous

Identified March 11, 2026More mineral →

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Physical properties

Formation & geological history

Formed through a process called pseudomorphism, where quartz replaces the fibrous mineral crocidolite (blue asbestos) over millions of years. This specimen retains the fibrous structure while becoming silica-rich. Primarily found in Precambrian iron formations.

Uses & applications

Predominantly used as a semi-precious gemstone for jewelry (cabochons, beads), decorative carvings, and as a popular specimen for metaphysical and mineral collectors.

Geological facts

Also known as 'Hawks Eye', it is the unoxidized version of the more common Golden Tiger's Eye. If the iron within the fibers oxidizes, the blue turns to gold. It exhibits a unique optical effect called chatoyancy, which creates a 'cat's eye' shimmering band across the surface.

Field identification & locations

Identify in the field by its characteristic chatoyant blue shimmer when rotated under light and its heavy mineral weight compared to glass. Major commercial deposits are located in South Africa, Western Australia, India, and Brazil.

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