metamorphic
Tumbled tiger’s eye
Quartz (SiO₂) with fibrous riebeckite/crocidolite inclusions
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; golden-brown chatoyant bands, vitreous to silky luster, microcrystalline quartz, no obvious cleavage, specific gravity about 2.64–2.71. The polished surface shows a reflective cat’s-eye effect from aligned fibers.
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Physical properties
Hardness 6.5–7 Mohs; golden-brown chatoyant bands, vitreous to silky luster, microcrystalline quartz, no obvious cleavage, specific gravity about 2.64–2.71. The polished surface shows a reflective cat’s-eye effect from aligned fibers.
Formation & geological history
A metamorphic quartz aggregate formed when crocidolite fibers were replaced and encased by silica during alteration, commonly in iron-rich environments. Most commercial material comes from the Precambrian formations of South Africa and Western Australia.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, and ornamental objects; it is popular in inexpensive jewelry and collections.
Geological facts
Its chatoyancy changes with viewing angle because light reflects from parallel fibrous inclusions. Blue-gray unaltered material is called hawk’s eye, while red-brown heat-treated material is often called ox-eye.
Field identification & locations
Identify it by its silky golden bands and moving cat’s-eye sheen, unlike uniformly colored glass or ordinary quartz. Common sources include South Africa, Western Australia, India, Brazil, and the United States.
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