Recent base metal discovery at the Hill 800 Prospect

Abstract

Hill 800 Prospect is located northwest of Licola, near the Jamieson River in the eastern highlands of Victoria. It was discovered in 1994 and is currently held under EL 3592 by Mount Wellington Gold N.L. (Mount Wellington Gold). The exploration model is for volcanic-hosted massive sulphides in the Cambrian Jamieson Volcanics. Mount Wellington Gold's interest in the area was sparked by new regional magnetic and radiometric data that became available in 1993 under the Victorian Initiative for Minerals and Petroleum. Investigation of potassium anomalies resulted in the discovery of gossans at Hill 800. Soil geochemical data show high gold values over Hill 800 and high copper values surrounding this, to the south and west. The best assay values in drillholes are 37 m @ 3.16 g/t gold from 0.5 m, and 6 m @ 1.1% copper from 253 m in HED1. The high gold values occur in an oxidised and altered cap near the top of Hill 800. The high copper values occur separately from the gold values, in altered volcanics. The geophysical surveys carried out by Mount Wellington Gold include: airborne radar (AIRSAR), airborne frequency-domain electromagnetics (DIGHEM), ground magnetics, time-domain electromagnetics (SIROTEM), induced polarization, downhole electromagnetics, downhole magnetometric resistivity (DHMMR), spontaneous potential and controlled source audio magnetotellurics (CSAMT). The gold and copper mineralisation currently detected at Hill 800 does not have a significant geophysical response. Responses recorded to date are generally from geological rather than mineralised sources. The latest induced polarization results accurately predicted pyrite enrichment (+- gold). A drilling target was defined from a 3-D model of the inverted 100 m line-spaced data. The induced polarization chargeability anomaly was associated with high resistivity, and when drilled, was found to be caused by disseminated sulphides (pyrite). The DHMMR survey on diamond drillhole HED4A indicates a conductive source, possibly massive sulphides, above the hole at about 460 m depth. The SIROTEM data also show subtle high conductivity at late times in this area. These data have many anomalies, which have not yet been effectively tested by the drilling program. Magnetic susceptibility measurements on rock chips from the drilling program indicate that the weathered and altered volcanics have lower susceptibility than the fresh volcanics - perhaps due to magnetite destruction associated with the alteration/weathering. The regional magnetics show a highly magnetic source beneath Hill 800, probably an intrusion. Modelling shows that this intrusion may come to within a hundred metres of the surface, so it is a likely source of the alteration fluids.