Home of Bullion Copper Mine, Barrow Creek, Barkly Region, Northern Territory, Australiai

Regional Level Types
Home of Bullion Copper Mine	Mine
Barrow Creek	Creek
Barkly Region	Region
Northern Territory	Territory
Australia	Country

The Home of Bullion copper mine is about 30 kilometres east of Barrow Creek, probably longer by road, in rugged hilly country. Access is difficult, and would need permission from the Neutral Junction Station/Tara indigenous community (not all of these communities accept such requests, or visitors). To reach travel 12 kilometres north-east of Barrow Creek to the community, then continue on a track north which then turns east. About 2 kilometres before a dam, a track branches south south-east, then south-west, east then north, as it navigates around a range of hills. There are several dry creek crossings. The site contains some open cuts, shafts, building foundations/ruins, three large rusting tanks, and tailings pile on the side of the hills.

Early mining in the upper levels describes vistas of azurite, malachite and bornite, and there is no doubt the deposit is rich in copper, but is too small to have seen modern mining. There is also rapid zoning at depth from secondary to primary ore at a lower grade, with the remote site also discouraging development. Several species have occasionally been seen as specimens including smithsonite, malachite, azurite, and calcite, amongst others, probably collected from the ore pile which remained at the site.

The deposit was discovered by William Garnett in 1923, who was also involved with the Hammerjack mine near Tennant Creek. Active mining however did not start until 1936 with a trial parcel of 110 tonnes. Lindsay Duffield and Co held the lease in 1946, then by a former agent of the company, W.F. Hartley. During this time it was under tribute to Ted Gordon, Reg Rattley, and Roy Cubitt, employing also two men. To 1949 the mine had produced 3185 tonnes of ore worth $95 238 at 22.5% Cu. Toby Becker was mining the deposit in the 1950's.

South Australian government geologist, Ward, examined the deposit in 1925 shortly after its discovery. Then Madigan in 1934 on behalf of the Central Australian Silver Lead and Copper Company NL, who sank shafts. For Mt Isa Mines Ltd, Blanchard examined the deposit in 1936; Sullivan, Brittingham and Thomson 1950, with a fairly comprehensive report; Bill 1953-1954; BMR 1950's Australian Geophysical Pty Ltd 1965; Drown 1992 for Aberfoyle Resources Ltd; and Goldstate Exploration Inc. 2001 to 2012, all examined the deposit.

The main ore mined was chalcocite between the 120-180 foot levels, which was then transported to Alice Springs and onwards to Port Kembla NSW for processing. There are four lodes named Main, East, South No. 1 and South No. 2. Production has been limited to the central part of the Main Lode, and several small parcels from South No. 2.

The Main Lode outcrops as gossan lenses across 480 feet, as three lenticular portions, up to 12 feet wide. These are connected by narrow channels down to mere filaments of mineralisation. Ore spurs branch off into the walls. The strike is variable laterally and at depth. The western end stops abruptly due to a shear, while the east end splits into narrow branches. Primary sulphides are found below 300 feet. In the Hanging Wall is a band of chlorite biotite rock up to 4 feet wide, with pug seams and some brecciation in the Hanging and Footwalls.

The oxidised zone shows limonitic gossan, ending sharply at the water table, marked by a white leached zone 2-4 feet thick. In places above are voids up to 2 feet wide, lined with limonite stalactites. Copper carbonates, oxide, and lead carbonates are found irregularly throughout the gossan.

The secondary sulphide zone is 120-220 feet depth showing sooty and massive chalcocite, with bornite, pyrite crystals remnants to one inch, marcasite, minor chalcopyrite, common cerussite grains, and some sphalerite. At depth the deposit becomes more pyritic, chalcocite rarer, with decreased copper grades.

The primary sulphide zone is below 220 feet, showing massive pyrite and marcasite, minor massive sphalerite, galena veinlets, with chalcopyrite up to 15% volume of some drill cores.

The East Lode is several hundred feet south-east of the Main Lode, on a parallel strike, outcropping boldly as a quartz vein up to 3 feet wide. The vein contains gossan patches, minor cuprite, un-named copper and lead carbonates. The east ends feathers into small quartz veins. Chalcocite is rare.

The South Lode No. 1 forms a bold outcrop of massive siliceous hematite which forms the capping to the ore, some Cu staining, with irregular sericite veinlets, the ore body 145 feet long by 50 feet wide, with bands of sericite schist. There is a small open cut at the western end. The south side of the lode is bounded by andalusite sericite schist, with bordering the north side is grit, sandstone, and a zone of brecciated and puggy schist indicating a fault channel. Between 137-178 feet, the source states is feeble copper mineralisation with copper carbonates, cuprite veinlets, trace native copper.

The South Lode No. 2 contains a 50 feet deep shaft, and small open cut down to 8 feet depth. There is little outcrop, with the open cut showing Cu staining. However parcels up to 19% Cu have been obtained. The ore body is contained in siliceous biotite hematite, and sheared sericite schist. At the 50 foot level is limonitic gossan, with copper carbonates sprinkled through.

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References