mineral

Tiger’s-eye heart

Chatoyant quartz (SiO₂), pseudomorphically replacing crocidolite

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; golden-brown to dark brown fibrous bands, vitreous-to-silky luster, opaque, with reflective chatoyancy (cat’s-eye effect). Quartz has a trigonal crystal structure, but the polished heart is shaped and has no visible cleavage.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Forms when blue asbestos-like crocidolite fibers are replaced by quartz during low-temperature alteration, commonly in Precambrian rocks. Major deposits occur in South Africa and Western Australia.

Uses & applications

Commonly cut into cabochons, hearts, beads, carvings, and ornamental objects; used in inexpensive jewelry and lapidary collections.

Geological facts

Its moving band of light results from aligned fibrous inclusions, not true crystal cleavage. Golden tiger’s-eye is distinct from blue hawk’s-eye, an incompletely altered precursor.

Field identification & locations

Identify it by brown-gold parallel bands and a bright reflective stripe that moves when the stone is tilted; polished surfaces are typically smooth and glassy. Common sources include South Africa, Australia, India, and Namibia.