Bauxite was found on Manus Island in 1952 by J.E. Thompson, Senior Resident Geologist, Territory of Papua and New Guinea, at three separate localities. At Lepatuan a dacite flow overlies bedded tuffs and both have been bauxitized. The former parent rock yields a porous granular bauxite containing about 1 percent silica, 55 percent alumina, 10-13 percent ferric oxide and 1 percent titania. Bauxite developed on the tuffs is nodular in character, and consists of gibbsite nodules embedded in soft clay-like bauxite. The composition of one sample of this bauxite is 11.7 percent silica, 51.0 percent alumina, 10.8 percent ferric oxide and 1.0 percent titania. The bauxite is forming at the present day by direct alteration of the dacite without an intervening clay zone, but the tuffs are kaolinized in the first stage of alteration. It is of high significance that bauxite can develop on small flat elevated areas (50 acres at Lepatuan) during the present weathering cycle. Essential conditions for bauxitic alteration to take place appear to be - (a) high mean temperature, high rainfall and dense vegetation, (b) relatively flat terrain, and (c) elevation above immediate surroundings to ensure adequate ground-water movement. Total resources of bauxite at Lepatuan are about 600,000 tons, and possible reserves are negligible at the other localities. Difficulties of access and distance from markets militate against commercial exploitation of the deposit, but prospects of finding more bauxite in the islands of the volcanic arcs of Bismark Archipelago cannot be lightly dismissed.
