metamorphic
Polished tiger iron (likely tiger-eye-rich banded stone)
Tiger iron: banded quartz (SiO₂), crocidolite-derived fibers, and iron oxides such as hematite/goethite
AI-generated identification · may be incorrectHardness about 6.5–7 (Mohs); brown-gold to black, with fine parallel bands and subdued chatoyant sheen when polished. It has a microcrystalline quartz structure, no obvious cleavage, and specific gravity roughly 2.6–3.0.
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Physical properties
Hardness about 6.5–7 (Mohs); brown-gold to black, with fine parallel bands and subdued chatoyant sheen when polished. It has a microcrystalline quartz structure, no obvious cleavage, and specific gravity roughly 2.6–3.0.
Formation & geological history
Forms through metamorphism and silicification of iron-rich, quartz-bearing rocks, commonly preserving alternating jasper, hematite, and tiger-eye layers; major deposits are Precambrian, especially in Western Australia. The exact specimen could also be banded jasper or iron-rich quartzite.
Uses & applications
Used for cabochons, carvings, beads, polished display stones, and ornamental objects; attractive pieces have modest lapidary value.
Geological facts
Tiger iron is prized for its dramatic natural banding and may show chatoyancy from aligned fibrous inclusions. Its appearance can overlap with banded jasper, ironstone, or polished quartzite.
Field identification & locations
Identify it by its very regular dark, golden-brown bands, quartz-like hardness, and possible silky reflection; a streak, hardness, and density test would distinguish it more confidently. Common sources include Western Australia, South Africa, Brazil, and India.
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