Exploration for possible economic hypogene base metal sulphide deposits associated with poorly exposed iron-rich linear outcrops, overlying faulted Archaean to Palaeoproterozoic basement which is obscured by extensive Cainozoic sedimentary cover rocks developed adjacent to the western shore of Lake Gilles, has consisted of aerial and ground geological mapping, bulldozer trenching of inferred gossans to obtain solid bedrock samples for geochemical analysis, and angled rotary percussion drilling (13 holes for a total of 760 feet) to depth beneath trenches cut into substantial gossans, greater than 40 feet wide, which gave significant base metal anomalies (Zn to 1200 ppm, Cu to 480 ppm, Pb to 700 ppm) in costean wall samples. Because of the high ground water table that was encountered unexpectedly, reflecting the area's broken ground and proximity to Lake Gilles, Asarco's drill evaluation of the basement to targeted depths of around 150 feet proved impossible to complete with the equipment on hand. The drilling penetration which was achieved showed that surface goethitic material passes into sparsely mineralised quartz kaolinitic material with depth, whereby the gossans either almost disappear or narrow markedly, i.e. they appear to be lensoidal in vertical section. Sulphides are absent, and metal assay values decrease sharply downwards in the drillholes. Therefore it was concluded that the likelihood of finding any mineralised structures at depth is slim, and does not warrant further drilling investigations.