Exploration for possible economic deposits of massive crystalline andalusite and sillimanite, formed within Palaeoproterozoic Willyama Complex muscovite-quartz schists and gneisses in an area of partly exposed basement north-west of Olary, has included 1:2000 scale geological mapping and detailed inspection of abandoned past surface workings, plus outcrop sampling and petrological determinations, and ore mineral beneficiation tests. At Morialpa, a persistent muscovite-quartz schist horizon approximately 500-600 m wide contains high grade sillimanite pods and lenses that are concordant with the rock foliation and are spatially associated with quartz pegmatites over a 1.2 km strike length. Eroded blocks of sillimanite of up to 400 kg weight have been exposed by deep surface weathering, and additional sizeable exposures are present in some areas of past surface mining. It is estimated that the largest size sillimanite pods seen may each contain up to 100 tonnes of massive ore. Andalusite occurrences which were mapped and sampled at the Ameroo Hill group of old workings appear to have a metasomatic origin, and have been metamorphically retrogressed to sillimanite-muscovite composition to varying degrees. At the Maggie claim a knotted muscovite-quartz schist horizon 30 m wide can be traced over a distance of about 700 m. This bed carries many small andalusite pods recorded as yielding weathered boulders ranging up to 100 kg in weight. Laboratory beneficiation tests performed on small bulk samples (to 150 kg) of sillimanite and andalusite from both Morialpa and Ameroo have established that the richer segregated ore will yield high grade concentrates (having 50% Al2O3 or higher, with low iron content) that could be sold into the local refractory raw materials market and would be competitive with imported products in terms of quality. An estimated 2000 tonnes of good andalusite ore is exposed on a hillside at Ameroo West, which could be utilised for pilot-scale beneficiation trials; however, the real concentration of mineralised pods distributed throughout the schists at Ameroo is still unknown, since no technique other than bulldozing costeans is available for establishing the presence and size of such pods. A firm resource of massive mineralisation in specific beds would need to be delineated in order to allow commercial mining.