Rock Identifier
Tumbled tiger’s-eye (Tiger’s-eye (chatoyant quartz), SiO₂, pseudomorphic fibrous quartz after crocidolite) — metamorphic
metamorphic

Tumbled tiger’s-eye

Tiger’s-eye (chatoyant quartz), SiO₂, pseudomorphic fibrous quartz after crocidolite

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; golden-brown to reddish-brown silky chatoyancy, vitreous-to-silky luster, cryptocrystalline quartz, no distinct cleavage, specific gravity about 2.64–2.71. The parallel fibers create a moving cat’s-eye band when rotated.

Identified More metamorphic
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Physical properties

Mohs hardness 6.5–7; golden-brown to reddish-brown silky chatoyancy, vitreous-to-silky luster, cryptocrystalline quartz, no distinct cleavage, specific gravity about 2.64–2.71. The parallel fibers create a moving cat’s-eye band when rotated.

Formation & geological history

Formed when quartz replaced fibrous crocidolite (blue asbestos) during low-grade metamorphism, preserving its fibrous texture; commonly associated with Precambrian rocks, especially South Africa’s metamorphic deposits.

Uses & applications

Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; attractive pieces have modest gemstone and collector value.

Geological facts

Its optical chatoyancy results from reflection along aligned fibers and is strongest with a centered, polished band. Blue hawk’s-eye is an earlier stage of the same alteration sequence.

Field identification & locations

Identify by its brown-gold color, silky linear sheen, and sharply shifting bright band under directional light; common sources include South Africa, Western Australia, India, and Namibia. Avoid aggressive cutting or inhaling dust, as imperfect material may retain fibrous inclusions.