Rock Identifier
Tumbled Tiger’s Eye (Quartz variety, fibrous SiO₂ with crocidolite pseudomorphs) — mineral
mineral

Tumbled Tiger’s Eye

Quartz variety, fibrous SiO₂ with crocidolite pseudomorphs

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; golden-brown to dark brown with silky chatoyancy, vitreous-to-waxy luster, and no prominent cleavage. The rounded, polished shape is human-processed; the dark areas may be iron-rich alteration or matrix.

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Physical properties

Hardness 6.5–7 Mohs; golden-brown to dark brown with silky chatoyancy, vitreous-to-waxy luster, and no prominent cleavage. The rounded, polished shape is human-processed; the dark areas may be iron-rich alteration or matrix.

Formation & geological history

Forms when crocidolite asbestos fibers are replaced by quartz during low-grade alteration, commonly in Precambrian metamorphic terrains. Major deposits are associated with the Northern Cape of South Africa, with additional material from Australia, India, and Brazil.

Uses & applications

Used for beads, cabochons, carvings, worry stones, and ornamental objects; it has modest jewelry and collector value.

Geological facts

Its moving cat’s-eye band results from reflection along aligned fibrous inclusions. Red varieties are called red tiger’s eye, while blue-gray material is hawk’s eye.

Field identification & locations

Identify it by the chatoyant stripe, brown-gold color, polished quartz-like hardness, and fibrous appearance; ordinary brown jasper lacks the silky optical effect. Commonly found as rounded lapidary pieces rather than natural crystals.