metamorphic
Polished tiger iron (likely)
Tiger iron: banded quartzite composed mainly of quartz, hematite, and crocidolite/amphibole; visual identification is provisional
AI-generated identification · may be incorrectTypically Mohs hardness 6.5–7, vitreous to silky luster, dense and opaque, with dark red-brown hematite/magnetite bands and golden-brown chatoyant quartz or iron-rich material. The wet, polished surface intensifies its strongly banded appearance.
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Physical properties
Typically Mohs hardness 6.5–7, vitreous to silky luster, dense and opaque, with dark red-brown hematite/magnetite bands and golden-brown chatoyant quartz or iron-rich material. The wet, polished surface intensifies its strongly banded appearance.
Formation & geological history
A metamorphic banded iron formation altered and silicified over geologic time, commonly Precambrian in age (roughly 2.5–1.8 billion years). Major material comes from Western Australia, especially the Pilbara region.
Uses & applications
Cut and polished for cabochons, carvings, display stones, and ornamental objects; it has little industrial use in this polished form.
Geological facts
The orange-brown and black pattern resembles tiger striping, while the metallic dark bands are commonly hematite or magnetite. The pictured piece could also be a related polished iron-rich jasper or brecciated jasper, which cannot be confirmed from one photograph.
Field identification & locations
Look for alternating red, gold, brown, and black bands, high polish, and quartz-like hardness; it should resist scratching by a steel knife. Common sources include Western Australia, South Africa, and India.
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