mineral
Tiger’s-eye (likely rough chatoyant quartz)
Quartz, SiO₂, with fibrous pseudomorphic alteration of crocidolite (often called tiger’s-eye)
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; golden-brown to reddish-brown, vitreous to silky luster, opaque, with fibrous banding and possible chatoyancy. The specimen appears rough and layered, though exact identification is uncertain from the image alone.
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Physical properties
Hardness about 6.5–7 Mohs; golden-brown to reddish-brown, vitreous to silky luster, opaque, with fibrous banding and possible chatoyancy. The specimen appears rough and layered, though exact identification is uncertain from the image alone.
Formation & geological history
Forms when quartz replaces weathered, fibrous crocidolite during hydrothermal alteration, preserving its parallel texture; major deposits are associated with Precambrian rocks of South Africa and Western Australia.
Uses & applications
Cut and polished for cabochons, carvings, beads, and ornamental objects; rough pieces are commonly collected. It has little industrial value compared with ordinary quartz.
Geological facts
The distinctive moving “cat’s-eye” sheen results from aligned fibers reflecting light. Red varieties are commonly called bull’s-eye or red tiger’s-eye and may reflect natural oxidation or heating.
Field identification & locations
Look for parallel golden-brown fibers, silky luster, and chatoyancy when a light is moved across the surface; a glass-scratching test can support quartz identification, but should be avoided on valuable specimens. Commonly found in South Africa, Australia, India, and Namibia.
