The Pilbara region comprises a large part of the ancient continental shield of Western Australia which is comprised of both Proterozoic and Archaean rocks. The Pilbara is overlain by the Proterozoics deposited in the Hamersley and Bangernall Provinces.

The BIF is a member of the ~620 m thick Brockman Iron Formation which makes up part of the 2.63 2.45 Ga Hamersley Group. The Hamersley Group comprises almost 2.5 km of consecutive sedimentary and volcanic rocks located within the ca. 80,000 km2 Hamersley Province of the Pilbara craton in North West Australia, approximately 1100 km north of Perth. In the lower part, it consists of dolomite, shale and BIF, while the upper part consists of dolerite, various lava types and BIF with minor amounts of tuffs and shales. Underlying the Hamersley Group, is the 2.78–2.63 Ga Fortescue Group, which consists of flood basalts and rhyolites. These volcanics were laid down on the uplifted and eroded Pilbara block. This volcanic succession may contain remnants of a Large Igneous Province (LIP).

The Brockman Iron Formation ofthe Hamersley Group is divided into four sub-lithostratigraphic units, namely the lowermost Dales Gorge Member (BIF), the Whaleback Shale Member, the Joffre Member (BIF), and the uppermost Yandicoogina Shale Member. After deposition, these laterally extensive BIF have all experienced minor folding and basinal uplift along with low-grade regional metamorphism – from burial prehnite–pumpellyite facies to greenschist facies.

General consensus exists regarding the depositional model of the Brockman Iron Formation. According to this model, the succession was deposited on a large, stable, and clastic-starved, continental platform, which was influenced by episodic inputs of fine-grained tuffaceous detritus.

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.