The possible untested economic base metal potential of a 10 mile long zone of airphoto-interpreted intense hydrothermal alteration of the Gawler Range Volcanics, which follows the Uno Fault near Margoon Dam, was investigated on the ground by sampling the rocks for geochemical and petrological studies. The alteration was found to be concentrated into two linear zones of tuffs and lava flow-breccias in the eastern part of the fault, and as more scattered irregular patches in the western part. The alteration is sometimes accompanied by intense silicification, but no associated base metal mineralisation was seen. The assay results obtained from 111 stream sediment samples and 114 selected rock chip samples collected in the area indicated only low background metal values, with some very slight base metal enrichment (to 2x background) in some of the altered rock types. Rarely, a metal content of the order of several 100s of ppm of copper and lead is found in iron-rich metaquartzites, but these appear to be of very limited size and are thought unlikely to be hosting massive sulphides. It was considered that the work done on this project had been sufficient to show that no economic base metal mineralisation exists within the alteration zone, and accordingly it was decided to surrender the ground.