metamorphic
Polished tiger iron
Tiger iron: banded quartz (SiO₂), red jasper, and crocidolite-derived fibrous iron oxides
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; glossy polished luster; rusty red, golden-brown, and dark gray-blue linear bands. It is opaque, fine-grained, and has no obvious cleavage; density is typically about 2.7–3.3.
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Physical properties
Hardness about 6.5–7 Mohs; glossy polished luster; rusty red, golden-brown, and dark gray-blue linear bands. It is opaque, fine-grained, and has no obvious cleavage; density is typically about 2.7–3.3.
Formation & geological history
A banded iron-rich metamorphic rock formed through silicification, iron deposition, and later metamorphism, mainly in Precambrian terrains roughly 2.5–3.5 billion years old. The blue-gray bands commonly represent altered crocidolite fibers, while red and gold bands are jasper and iron oxides.
Uses & applications
Used for cabochons, carvings, polished palm stones, bookends, and ornamental slabs; it is generally decorative rather than industrial. Attractive, strongly contrasting specimens have moderate collector appeal.
Geological facts
Its vivid “tiger-stripe” appearance resembles tiger’s-eye but is a composite rock rather than a single mineral. Polishing accentuates the hematite/goethite reds and golden quartz-rich bands.
Field identification & locations
Identify it by its hard, dense body and irregular, parallel red-gold-blue banding; it will not scratch easily with a steel knife. Major material comes from Western Australia, especially the Pilbara region.
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