Middleback Ranges lie 26 miles (42 kilometers) west of Whyalla on the Eyre Peninsula in South Australia. They extend from Iron Knob in the north to Iron Duke in the south—a distance of 40 miles (64 kilometers). The present form of the ranges has resulted from the folding of the rocks, followed by long periods of erosion. The ranges are composed mainly of iron-rich rocks, in which local concentrations of hematite iron occur.
The ore was first mined in 1897 for ironstone flux, which was used for lead smelting at Port Pirie. Since 1901, the ore has been mined for use in Australia’s steel industry. Reserves of commercial grade ore in the Middleback Ranges are estimated to be 215 million tons (195 million metric tons), of which about 81/2 million tons (7.7 million metric tons) are mined annually.
