The Proterozoic Curnamona Province extends across eastern South Australia and western New South Wales, cropping out in the Willyama, Mount Painter and Mount Babbage Inliers. Most of the Province is, however, obscured by younger sedimentary cover. The Province comprises a sequence of late Palaeoproterozoic metasedimentary and metavolcanic rocks (Willyama Supergroup), and local metamorphosed intrusives, together with early Mesoproterozoic volcanic and sedimentary rocks and granitic intrusives. The Willyama Inlier, the largest area of outcrop in the Curnamona Province, occurs as a series of semi-isolated blocks in eastern South Australia and western New South Wales; it is comprised of the Olary Domain and Broken Hill Domain. In South Australia, most of the rocks of the Willyama Supergroup are referred to as the Olary Domain (OD), and they are distinguished from the adjacent south-western portion of the Broken Hill Domain (BHD) by different lithological, magnetic and gravity characteristics. The boundary between the two domains is marked by a NE-trending magnetic low zone. The nature of the boundary is obscured by extensive Recent to Tertiary cover, but in part (e.g. west of Broken Hill) is manifest by the Mundi Mundi Fault. Outcrops of the Olary Domain occur as a series of isolated blocks, separated by corridors of the Neoproterozoic Adelaide Geosyncline sedimentary sequence and partly blanketed by Tertiary to Recent sediments and regolith. The OD is largely composed of low to high grade regionally metamorphosed and deformed late Palaeoproterozoic sedimentary and minor volcanic and intrusive rocks. The Palaeoproterozoic rocks have been intruded by extensive volumes of early Mesoproterozoic granitoids and scattered mafic dykes of Neoproterozoic age. Low grade metamorphosed Neoproterozoic sedimentary rocks of the Adelaide Geosyncline unconformably overlie, or are faulted against the OD to the west, south, and to a limited extent, the north. Aeromagnetic and gravity data, regolith studies and drilling results infer that the OD extends to the north for many tens of kilometres under cover along the Benagerie Ridge towards the central part of the Curnamona Craton. Data from the Benagerie Ridge imply that the degree of deformation and metamorphism of the OD sequence is less than that to the south. Cover over the OD on the Benagerie Ridge is mostly Cainozoic, but in places includes Cambrian and Adelaidean rocks. Work on the geology and mineral deposits of the OD indicate that there are many similarities, as well as differences between the OD and BHD, in terms of stratigraphic units, rock types, metamorphism, intrusive history and mineral deposits. The Willyama Supergroup has been interpreted as having been deposited in a failed Palaeoproterozoic rift, which was subsequently deformed and metamorphosed. The central part of the former rift may be largely present in the BHD, bounded to the west by the Mundi Mundi Fault and the gravity and magnetic discontinuity southwest of Cockburn, and to the east by the Redan Geophysical Zone. The OD portion of the Willyama Supergroup may represent a rift-margin shelf setting, and although a detailed palaeoenvironmental synthesis has not been attempted, the sequence may be consistent with deposition in a lacustrine to marine, including possible sabkha setting, deepening upwards into marine strata. Although coeval magmatism was largely felsic, there is evidence for bimodality.