metamorphic
Tumbled tiger’s-eye
Tiger’s-eye (chatoyant quartz), SiO₂, pseudomorphic fibrous quartz after crocidolite
AI-generated identification · may be incorrectMohs 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.
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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.
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