metamorphic

Tiger iron (polished)

Banded iron formation composed mainly of hematite, magnetite, and quartz/jasper

AI-generated identification · may be incorrect

Mohs hardness about 6–7; elongated polished pebble with metallic to silky dark gray iron-oxide bands and rusty brown-red jasper, with minor vitreous quartz luster. It is dense, opaque, fine-grained, and typically lacks visible cleavage.

Identified September 4, 2026More metamorphic →

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Physical properties

Formation & geological history

Tiger iron formed from ancient Precambrian chemical sediments later metamorphosed and silicified, commonly about 2.2–2.6 billion years old. Its stripes result from alternating silica-rich jasper/quartz and iron-oxide layers.

Uses & applications

Used for cabochons, beads, carvings, worry stones, and ornamental objects; it has little industrial value in polished form.

Geological facts

The name refers to its tiger-like brown, gold, black, and gray banding. Unlike ordinary tiger’s-eye, tiger iron commonly contains true ironstone bands and red jasper.

Field identification & locations

Identify it by alternating reddish-brown jasper, gray-black hematite/magnetite, high density, and a smooth polish; a magnet may respond weakly to magnetite-rich areas. Classic material comes from Western Australia, especially the Pilbara region.