metamorphic
Polished tiger’s-eye
Quartz variety with fibrous crocidolite pseudomorphs; mainly SiO₂
AI-generated identification · may be incorrectMohs hardness 6.5–7; golden-brown to yellow chatoyant bands, vitreous-to-silky luster, granular microcrystalline quartz, and no prominent cleavage. The polished surface shows strong cat’s-eye shimmer when moved under light.
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Physical properties
Mohs hardness 6.5–7; golden-brown to yellow chatoyant bands, vitreous-to-silky luster, granular microcrystalline quartz, and no prominent cleavage. The polished surface shows strong cat’s-eye shimmer when moved under light.
Formation & geological history
Forms when blue asbestos-like crocidolite fibers are replaced by quartz during low-grade metamorphic alteration, commonly in Precambrian iron-rich rocks. Major deposits occur in South Africa and Western Australia.
Uses & applications
Cut into cabochons, beads, carvings, and ornamental objects; widely used in inexpensive-to-moderate jewelry and lapidary collecting.
Geological facts
Its optical chatoyancy comes from aligned fibers, producing a narrow reflected band resembling a cat’s eye. Blue-gray hawk’s-eye and red-brown varieties can occur in the same geological systems.
Field identification & locations
Identify it by silky parallel bands and a moving cat’s-eye effect; unlike jasper, it typically shows directional chatoyancy and a quartz-like hardness. Common sources include South Africa, Australia, India, and Brazil.
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