Annual report MLN 13, 1 July 1989 to 30 June 1990

Abstract

During the 1989-90 financial year 2,554,808 BCM of material was mined. Mining work involved blasting, pit slope stability, tailings dam Construction and milling. A total of 1,133,976 tonnes of ore totalling 2.66 grams per tonne gold was treated in the CIP circuit yielding 2,304kg gold and 721.4kg silver. The average gold recovery was 77.2 percent. Heap leaching saw 551,002 tonnes of ore crushed yielding 325.2kg of gold. Exploration at North Enterprise involved the drilling of 29 percussion holes to the base of oxidation across the axis of the enterprise anticline. Assay results were generally disappointing with the majority being less than 0.5 grams per tonne Au. Some spotty grades were obtained from the western limb and close to the anticlinal axis indicating minimal potential for bulk oxide ore but some potential for leachable material. A total of 4 diamond drill holes were drilled at the south-east Enterprise for the purpose of determining the position of the Enterprise syncline, and to gain a better understanding of the structure and stratigraphy in this area. The syncline was found to pass out of the pit and continues south where it crosses the Stuart highway. Ten diamond holes were drilled at the South Enterprise designed to intersect down plunge mineralisation of the Enterprise saddle reef system and to define the structure and lithology in this area. Evidence from this programme indicates there is a significant increase in the plunge of the anticlinal axis increases from 11300N. This has been caused by the effect of South Enterprise Fault. At the Czarina Anticline 9 diamond holes were drilled along to test the East limb of the structure, and RC and percussion drilling were used to evaluate the potential Au resource in both the oxide and primary zones. At the southern end of the anticline there is only the possibility of a low grade marginal resource in the oxide. At the northern end of the structure there is a resource of 850,000 t at 1.7 grams per tonne in the oxide zone and 1,400,000 t at 2.1 grams per tonne in the primary zone. Percusion drilling at Eleanor proved inconclusive but did demonstrate the highly patchy nature of gold occurrences. This was followed by diamond drilling which revealed visible gold within quartz veins in the grit-greywacke sequence.