The iron ore deposits of-the Port Hedland distract of North-Western Australia are associated with banded-sedimentary iron., formations that.form part of the local succession. of folde.d..and faulted Archaean volcanic and sedimentary. rocks., The iron formations are regarded as the pr.otore,beds or sources of.the. iron which became;.,c,o.ncentrated by supergene.,processes. to form c,omznercial grade.. iron ore deposits,, ;-; Iron oxide ' deposit's occurring in"situ' within' the prot'ore beds are considered to be of residual--repplacement,origin`, due to supergene leaching of gangue minerals and deposition of secondary iron oxides in their'place'. Two types of deposit have been recognized. Lode deposits are deep lenses of massive hematite located adjacent to major, fau.lts... - These; deposits are-thought-to be very.,,old' and-to: have originated by supergene processes:.. during the, long: period of_ erosion represented- by the major, unconformity between the, Archaean .rocks and the, over!.