mineral
Tumbled tiger’s-eye
Quartz variety, fibrous golden-brown SiO₂ (pseudomorphic quartz after crocidolite)
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; golden-brown chatoyant bands, vitreous to silky luster, translucent to opaque, and no prominent cleavage. Its moving cat’s-eye sheen results from aligned fibrous inclusions and polished surfaces.
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Physical properties
Hardness 6.5–7 Mohs; golden-brown chatoyant bands, vitreous to silky luster, translucent to opaque, and no prominent cleavage. Its moving cat’s-eye sheen results from aligned fibrous inclusions and polished surfaces.
Formation & geological history
Forms when crocidolite asbestos fibers are replaced by silica during weathering, commonly in iron-rich metamorphic rocks; the best-known material formed in Precambrian terrains of South Africa and Western Australia. The pictured specimen is tumbled and polished.
Uses & applications
Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; polished pieces are popular among mineral collectors.
Geological facts
Tiger’s-eye is a pseudomorph: quartz preserves the fibrous texture of an earlier mineral. Blue hawk’s-eye is an incompletely altered precursor, while reddish tones may result from heating or oxidation.
Field identification & locations
Identify it by its silky, mobile chatoyancy and parallel golden bands; unlike synthetic glass, the fibers and banding are irregular. Common sources include South Africa, Australia, India, Namibia, and Brazil.
