metamorphic

Polished tiger iron

Tiger iron; interbanded jasper, hematite, and crocidolite/quartz

AI-generated identification · may be incorrect

Hardness about 6.5–7 (hematite-rich zones can be softer); brown-gold, black, red, and cream bands with silky to vitreous luster. The specimen appears rounded and polished, with dense, layered fibrous/crystalline structure and no obvious cleavage.

Identified September 2, 2026More metamorphic →

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Physical properties

Formation & geological history

A banded iron formation altered by metamorphism and silicification, producing alternating jasper/quartz, hematite, and riebeckite (crocidolite) layers; commonly Precambrian, roughly 2.5–1.8 billion years old. Classic material comes from the Hamersley Range of Western Australia.

Uses & applications

Used for cabochons, carvings, polished stones, and lapidary collectibles; attractive pieces are valued for strong contrast and chatoyant-looking bands.

Geological facts

Its distinctive pattern combines three major components: red-brown jasper, metallic hematite, and golden-brown tiger-eye-like material. The dark metallic portions may weakly attract a magnet if magnetite is present.

Field identification & locations

Identify by dense, irregular parallel bands of earthy red-brown, black, gold, and cream, a smooth polish, and high durability; it is much heavier than similarly colored wood. Avoid inhaling dust during cutting, especially where fibrous riebeckite is present.