Although abundant iron ore was reported in Western Australia in the 1890s, only a few easily accessible deposits attracted interest before 1960. Intensive exploration since 1960 has increased the indicated and inferred reserves from a few hundred million to 24 10⁹ MT. Most of the ore is high grade, and 95% of it is in the northwest of the state. Export began in 1965, and in 1974 six mines were operating solely for export, one for domestic use, and two for both purposes. Total production in 1973 was 74 million MT, and the total export tonnage (1965-73), including pellets, was 281.5 million MT.

Geologically, there are three distinct ore types: hematite enrichment ore, pisolitic limonite ore, and sedimentary ore. Hematite enrichment ore developed during Proterozoic time within both Archean and Proterozoic banded iron formations (BIFs). Structurally controlled deep-water circulation removed Si, Ca, Mg, Na, K, and CO₂, and introduced Fe, to effect metasomatic conversion of the BIFs to hematite and develop stratiform orebodies, a few of which exceed 1 10⁹ MT. Secondary development of goethite has lowered the grade to about 63.5% iron. Pisolitic limonite formed along Tertiary drainages off the Hamersley basin. This material now caps sinuous mesas; it contains 40-60% iron. Sedimentary ore is qu ntitatively minor, and is restricted to the small high-grade Proterozoic coastal deposits of Yampi Sound.

A total capital investment of A$1,570 million since 1965, the extent and quality of Western Australian ore reserves, and proximity to the Japanese market--all justify confidence that the present export status will be maintained; however, several problems must be solved before export and domestic-processing growth rates can increase.