gemstone

Tumbled tiger’s-eye

Quartz variety: fibrous chalcedony/quartz pseudomorph after crocidolite, SiO₂

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; golden-brown to reddish-brown silky chatoyancy, vitreous-to-waxy luster, cryptocrystalline quartz, no visible cleavage, specific gravity about 2.64–2.71. The polished surface shows reflective bands that shift with illumination.

Identified September 18, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when blue asbestos-like crocidolite fibers are replaced by quartz, commonly during weathering and silicification; most gem material formed in Precambrian rocks, especially South Africa’s Northern Cape. It is typically polished or tumbled, as shown.

Uses & applications

Used for cabochons, beads, carvings, worry stones, and ornamental objects; attractive specimens are collected for their chatoyant banding.

Geological facts

Its moving cat’s-eye effect is called chatoyancy and results from aligned fibrous inclusions. Red tones may reflect heat treatment or iron-rich alteration.

Field identification & locations

Identify it by its glassy silky bands, strong light-direction-dependent shimmer, and lack of cleavage; distinguish it from glass by its hardness and natural irregular banding. Common sources include South Africa, Western Australia, India, Brazil, and the United States.