Ore Deposit Information

This mineralised zone is currently defined by illegal, artisanal mining which initially consisted of a blanket of surface workings over an area of 400m by 200m. In June 2005, mining was more restricted, with several adits and underground shafts working lodes using small mills, the size of 44 gallon drums, extracting gold by amalgamation with mercury from selected ore. It was reported in August 2005 that, with the commencement of the wet season and better water supplies, free gold was being won by placing sluice boxes and mats in the creeks.

The artisanal workings extend over a vertical elevation of over 100m. The workings are terminated in the east, in a valley infilled with a post-mineralisation basalt flow of the Quarternary-age Nalesbitan Volcanics, and also where shafts intersected a high water table, preventing mining.

There are very few good outcrops, and the few than can be observed are on the steep slopes of the northeastern edge of Nalesbitan Hill at the Millsite locality, which is at the higher western end of this lode system. At this locality there is evidence of massive slumping of the pervasively siliceous, gold-mineralised, hydrothermal-phreatic breccias of the Nalesbitan Shear lode system.

The most relevant information on the Millsite-Singko lode system comes from detailed laboratory studies of rock samples collected in 1999 from illegal mining operations, and recent grab samples collected from two working adits in the eastern, Singko, sector.

There are three stages of alteration and associated mineralisation. The early stage consists of chlorite-sericite-quartz and disseminated pyrite alteration, which is overprinted by pervasive silicification. The main stage is fracturing with stockwork and/or sheeted veining of quartz-massive copper sulphides, including initial bornite-chalcopyrite and later tennantite-enargite. Advanced  argillic alteration typical of high sulphidation arsenical sulphides (e.g. enargite) is only locally present at Millsite, and is absent in the topographically lower, eastern Singko lodes. Gold occurs as discrete inclusions in bornite. Late stage primary chalcocite occurs in quartz veins and vughs, or as rims or replacing pre-existing sulphides. Late stage drusy quartz veins contain bismuth tellurides, gold and, locally, covellite, a high sulphidation copper sulphide.

Mineralised samples recently collected from the Singko adits are unbrecciated, and massively silicified with abundant disseminated pyrite and lesser amounts of a fine-grained dark (copper) mineral cut by 0.5 to 1cm conjugate vein sets of siliceous, dark massive copper sulphides (tennantite). Veining represents 5 to 7% of the samples. Similar veining collected from the Singko locality in 1999 assayed 1.6 to 24% copper and 1.2 to 14.8 g/t gold. A large sample recently collected from an adit assayed 3.1% copper, 10 g/t gold and 47 g/t silver.

There is evidence that there is an increase in copper mineralisation at the lower elevations of the eastern Singko lodes, suggesting vertical mineral zonation in these veins. Petrographic studies provide details of the mineralogical complexity of a major multi-stage hydrothermal system, with overprinting of an early high-temperature copper-gold sulphide vein/lode mineralisation by lower temperature intermediate to high sulphidation-low arsenic epithermal copper-gold mineralisation, and late stage epithermal auriferous quartz veins.

Structurally, the main Millsite-Singko sulphidic lodes in the south west are intersected by the Nalesbitan Hill siliceous breccias. The latter cross-cutting gold mineralised zone is clearly a younger event.

Recent drilling (ND1) indicates that the northwest continuation of the high-grade copper lode system may only extend west of the Millsite valley (and the inferred fault, Figure 9 ) at a vertical depth below 200m.

The high grades of lodes and veins worked by the illegal miners in the Millsite-Singko mineralised area are illustrated by recent sampling programs (Section 5.1.2). The current drilling program is defining the potential of this zone.

RobSearch Australia has previously estimated that the central, 400m by 200m, Millsite-Singko zone has a potential exploration target to 150m vertical depth for approximately 25 million tonnes of  ineralisation grading between 1.5 and 3 g/t gold, with an additional significant copper grade, perhaps in the order of 0.5%. Based on recent sampling of workings ( Figure 9 ), it is suggested that the stockwork copper-gold veined mineralisation could have a width in the order of 50m to 150m and strike length of 200m to plus 300m length. The zone appears to be open to the east below younger basalt cover for a possible further 200m.

These dimensions indicate an exploration target in the range of 5 to 30 million tonnes, but with recent sampling indicating higher grades possible (3 to 10 g/t gold, 1 to 3% copper) in, at least, part of the lode system.

Photos, Diagrams & Map of Mine Site

Figure 9 - Bagong Dose Proposed Drilling Program

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