The Hope Downs mine is located in the Hamersley Group which forms the middle layer of Mount Bruce Group in the Marra Mamba Iron Formation.

The Marra Mamba Iron Formation is the lowermost unit of the Proterozoic Hamersley Group in the northwestern part of Western Australia.

The Marra Mamba Iron Formation varies considerably in thickness, as based on sections measured in the field; however, not enough drill hole data are available to provide a quantitative assessment of its thickness variation throughout the Hamersley Range. Trendall and Blockley repoft a thickness range of 183 to 229 m based on sections mearPresent address: Department of Geology, Georgia State Univcrsity, Atlanta, Georgia

Others report thicknesses that range from a minimum of 15 m to 183 m (Macleod, 1966) for sections in different parts of the Hamersley Range. The Marra Mamba lron Formation is underlain by the Jeerinah Formation which is the uppermost member of the Fortescue Group. This group may be as much as 3660 to 4270 m thick and consists of shales and cherts in the upper part.

All of Hamersley Iron's mines are conventional open pits. Ore is loaded into haul trucks by shovels, hydraulic excavators or front-end-loaders, and transported to the primary crusher. It is then processed in a crushing and screening plant to produce fine ore and lump ore.

At Mount Tom Price, a high-grade plant produces lump product, fines and oversize. The oversize is returned for tertiary crushing after which it becomes part of the feed to the product screens.

At Paraburdoo, the fine ore stream from crushing and screening is wet screened and hydrocycloned to remove slimes. The Paraburdoo fines processing plant (PFPP) improves the quality of fines by reducing gangue impurities, particularly alumina. The gravity separation system segregates the magnetite from haematite.