metamorphic
Polished banded stone, likely tiger’s-eye
Tiger’s-eye quartz (fibrous chalcedony/quartz, SiO₂), possibly iron-rich quartzite
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; brown-gold silky bands with chatoyancy, vitreous to silky luster, and no obvious cleavage. The rounded, polished surface obscures grain and crystal structure.
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Physical properties
Hardness about 6.5–7 Mohs; brown-gold silky bands with chatoyancy, vitreous to silky luster, and no obvious cleavage. The rounded, polished surface obscures grain and crystal structure.
Formation & geological history
Forms when crocidolite asbestos fibers are pseudomorphed by quartz and oxidized to golden-brown iron oxides, generally during low-grade metamorphism; commonly associated with Precambrian rocks. The specimen appears tumbled or polished.
Uses & applications
Used for cabochons, beads, carvings, decorative objects, and inexpensive collector specimens; not typically used as structural stone.
Geological facts
Its moving cat’s-eye sheen results from aligned fibers reflecting light. Blue varieties are called hawk’s-eye, while red-brown material is often called bull’s-eye.
Field identification & locations
Identify by parallel silky bands and a bright narrow reflection that moves when the stone is tilted; common sources include South Africa, Australia, India, and Brazil. A definitive identification requires a close examination or gemological testing.
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