The iron-rich rocks of South Australia have been classified into six deposit types - residual, chemical sedimentary iron formations, Fe-skarn and, of lesser significance, hydrothermal, clastic and magmatic. Production has been overwhelmingly from high grade residual deposits located in the Middleback Range, northern Eyre Peninsula. These deposits are of national historical significance, and were the main source of ore for Australia's iron and steel industry from 1915 to the early 1960s. Production from all other deposit types has been relatively insignificant in terms of mined tonnages and contribution to the State's economy. Low grade sedimentary iron formations and Fe-skarn deposits form a neglected iron ore resource of State and national significance. The residual deposits in the Middleback Range are of Palaeoproterozoic age, with the larger deposits at Iron Monarch, the Iron Baron mining area and Iron Duke having collectively yielded more than 200 million tonnes (Mt) in 85 years of mining. Current production of 2.7 Mt/year is from Iron Duke and neighbouring deposits at Iron Duchess and Iron Knight. The total remaining proven reserves are 26 Mt. Recent discoveries of similar Palaeoproterozoic haematite deposits occur under a thin cover of younger sediments at the Wilgerup prospect (central Eyre Peninsula) and Buzzard prospect (northern Gawler Craton). From 1886 to 1915, 850 000 t of ore were mined for use as flux in the smelting of base metals from many small scattered residual deposits. The most important was Iron Knob in the Middleback Range; minor deposits were mined in the Adelaide Geosyncline and Olary Province. Most mines closed down at the turn of the century when production became centred on the Iron Knob mine. Minor production was recorded from small residual limonite-goethite deposits which were worked for ochre used as pigment. Chemical sedimentary iron formation, in particular banded iron formation (BIF), is widespread in several regions of the State. BIF with magnetite as the dominant iron oxide is readily recognised by its magnetic signature. BIF of Archaean age occurs in the Gawler Craton, with its best expression in the Warramboo-Kopi district (central Eyre Peninsula) and Mount Christie region (northern Gawler Craton). Archaean BIF is of moderate to high metamorphic grade and may offer advantages in beneficiation due to a relatively coarser grainsize. BIF of Palaeoproterozoic age is the most significant low grade iron ore resource in the State, particularly within stratigraphic units of the Middleback Subgroup and Wilgena Hill Jaspilite. The best prospects are the Middleback Range, Hawks Nest and Giffen Well. Exploration at Hawks Nest initially outlined near-surface, magnetite-rich BIF with inferred and indicated resources of 600 Mt to 130 m depth, grading 36% Fe. Resources at Giffen Well are estimated at 240 Mt grading 36% Fe. There appears to be potential for significant resources of magnetite-rich Palaeoproterozoic BIF in the Mount Woods Inlier. Exploration is minimal, and the BIF is not correlated with any certainty with Palaeoproterozoic BIF from other regions. Thickness estimates vary from a few metres to a maximum of 90 m, and metamorphic grade is described as moderate to high. Aeromagnetic images indicate several prospects with strike lengths of tens of kilometres. Palaeoproterozoic BIF is widespread in the Olary Domain where it occurs at various stratigraphic levels in Willyama Supergroup rocks as thin, discontinuous horizons. Its potential appears to be limited by poor grades and the small size of the prospects. Other occurrences of BIF on northern Yorke Peninsula, the Peake and Denison Ranges, and the Musgrave Block appear to have limited potential. Large masses of Fe-rich skarns have been discovered along the eastern margin of the Gawler Craton, with prospects identified within the Mount Woods Inlier, then southwards for 650-700 km, extending through the Andamooka Magnetic Complex and into the Moonta-Wallaroo district. The contained iron within this deposit type is enormous; the potential for mineable resources of low grade ore appears to be significant for both haematite-rich and magnetite-rich varieties. This deposit type is commonly polymetallic, with potential for economic levels of other metals; the best example is the Olympic Dam deposit, with an estimated 2 billion tonnes of contained iron.