metamorphic
Polished tiger iron
Tiger iron; interlayered hematite–jasper–crocidolite/quartz rock
AI-generated identification · may be incorrectHardness about 6–7 Mohs; dark brown to reddish-gold banding, opaque, with silky to vitreous polished luster. The rounded specimen is a tumbled or polished piece, showing fine concentric iron-rich layers rather than distinct crystals.
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Physical properties
Hardness about 6–7 Mohs; dark brown to reddish-gold banding, opaque, with silky to vitreous polished luster. The rounded specimen is a tumbled or polished piece, showing fine concentric iron-rich layers rather than distinct crystals.
Formation & geological history
A banded metamorphic rock formed from alternating jasper/chert, hematite, and fibrous quartz-rich layers, commonly associated with Precambrian iron formations roughly 2.2–2.5 billion years old. Metamorphism and iron oxidation produced its distinctive bands.
Uses & applications
Used as a lapidary stone for cabochons, carvings, bookends, and polished collectibles; occasionally marketed in jewelry. It has little structural or industrial value as a small specimen.
Geological facts
Its golden chatoyant bands can resemble tiger’s-eye, but tiger iron is a composite rock containing jasper and hematite as well as quartz. The iron-rich layers create the brown, red, and gold appearance.
Field identification & locations
Identify it by dense weight, opaque alternating bands, and hardness sufficient to scratch glass; it should not fizz in dilute acid. Classic material comes from Western Australia, especially the Pilbara region, and similar rocks occur elsewhere in Precambrian iron formations.
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