mineral

Tumbled tiger’s-eye

Tiger’s-eye quartz, fibrous chalcedony/quartz (SiO₂) with crocidolite pseudomorphs

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; brown to golden bands, vitreous-to-silky luster, opaque, with chatoyant (“cat’s-eye”) reflections caused by aligned fibers. It has trigonal quartz structure and no prominent cleavage; specific gravity is about 2.6–2.7.

Identified September 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms when blue asbestos-like crocidolite fibers are replaced by quartz during hydrothermal alteration, commonly in banded iron-rich rocks. Major deposits formed in Precambrian rocks, especially near the 2.0-billion-year-old formations of South Africa and Western Australia.

Uses & applications

Used for inexpensive cabochons, beads, carvings, tumbled stones, and ornamental objects; it has minor decorative and collector value rather than major industrial use.

Geological facts

The golden optical effect is chatoyancy, strongest when the stone is cut parallel to its fibrous bands. Blue-gray hawk’s-eye and red-toned variants may occur in the same material.

Field identification & locations

Identify it by its silky, moving band of light, brown-gold parallel fibers, and hardness sufficient to scratch glass. Common sources include South Africa, Western Australia, India, Brazil, and the United States.