An area covering 24 square km of private land situated approximately 10 km east of Truro township was taken up by Asarco under a number of privately negotiated option agreements to acquire the relevant mineral rights, should an economic base/precious metal occurrence be demonstrated at the so-called 'Truro prospect'. Here, at the end of 1969, Asarco had found a mineralised gossan surface exposure 12 m wide that on testing was seen to contain up to 0.2% Cu, 0.3% Pb and 0.5% Zn. This gossan and another, smaller such outcrop are developed in Cambrian argillaceous metasediments along part of a north-south trending alluvium-covered fault zone which defines the eastern margin of a tightly folded syncline containing these rocks, that is juxtaposed further eastwards against older Adelaidean bedrock subcropping Tertiary Murray Basin cover sediments. A ground magnetic survey and an induced polarisation/resistivity survey were carried out in an attempt to map the continuation of the gossanous horizon under cover. The magnetic readings indicated a strong anomaly lying parallel to and slightly to the east of the strike direction of the outcropping gossans, while the IP results also indicated a strong conductivity anomaly aligned parallel to the magnetic anomaly but generally removed to the west of the gossan feature. Several of the IP anomalies existing close to the gossan outcrops were selected for shallow rotary percussion drilling to an intended depth of about 60 m. However, in all cases the drilling was terminated prematurely because of influx of groundwater, leading to failure in recovery of drill cuttings from the holes. This happened at drilling depths of between 15 and 45 m. 14 drillholes were attempted, for a total penetration of 460 m. Logging and sampling of the rock sequence encountered has shown that the IP anomalies arise within a graphite-bearing shale carrying pyrite mineralisation with contained average base metal values of the order of 50 ppm Cu, 60 ppm Pb and 110 ppm Zn. Drillholes put down at the main gossan outcrop trend demonstrated that this is a surface haematite-goethite, partly boxworked capping to a 12 m wide zone of lightly sulphide-mineralised, oxidised schist having limited strike extent. It is inferred that, where found, the mineralisation has been localised by later-formed cross - structures to the target fault zone. The existence also of microdiorite and andesitic intrusive lenses along this fault zone, with possible associated magnetite metamorphic segregations, may account for the observed linear magnetic anomaly. On the basis of the geological, petrological and geophysical data newly gathered, it has been concluded that the chance of locating economic base metal massive sulphide accumulations at the Truro prospect is fairly remote.