Gecko Mine (Explorer 1), Tennant Creek, Barkly Region, Northern Territory, Australiai

Regional Level Types
Gecko Mine (Explorer 1)	Mine
Tennant Creek	Creek
Barkly Region	Region
Northern Territory	Territory
Australia	Country

A copper-bismuth-gold deposit in Proterozoic ironstones.

Copper mine with minor gold, silver, bismuth and selenium. It has formed in an anticlinal structure. The ironstone ore body is hosted by shale, greywacke, and sedimentary breccia. The ironstone is a magnetite-chlorite core, with an outer magnetite-hematite envelope. Dolomite-talc cuts the envelope, above and partly adjacent to the ironstone pods. Copper ore is contained in chalcopyrite in massive magnetite.

The anomaly was pegged as Explorer 1 by Peko Wallsend in 1959, and first drilled in 1960. A mineable resource was identified by 1970, with underground production beginning in 1975. The mine closed late 1981 due to low copper prices. Peko re-opened the mine from the late 1980's to early 1990's.

The deposit shows an early oxide stage precipitating magnetite, hematite, quartz, chlorite, which was all then foliated. Secondly a sulphide stage depositing Cu-Au-Bi as gold, chalcopyrite, Bi minerals, chlorite, quartz, and hematite converted from magnetite. Finally a minor carbonate stage of carbonate, talc, galena, sphalerite, and alteration of chalcopyrite to bornite and covellite. Gold is found in a weakly zoned area at the top of the ore body in a sulphide tongue to the K44 ore body. Copper mineralisation is found in a weakly zoned chalcopyrite-hematite rich deposit. Chalcopyrite has converted to bornite, chalcocite and covellite in the supergene zone of the copper bearing ironstone.

Pyrite is common in and near the deposit. At level 4 on the Footwall is a 5-10 cms unit of abundant pyrite crystals. These are also found in the sedimentary breccia, and at level 2 Hanging Wall drive. Skeletal pyrite crystals are found in breccia fragments, matrix, and in a 10 metre zone bordering the ironstone.

The mine is 26 kilometres north north-west of Tennant Creek, via the Warrego Road, then a further 4 kilometres north of the road. A headframe, two large sheds, and tailings pile remain at the location at the time of writing. There appears to be a small test pit 500 metres to the north-east.

Emmerson Resources has explored from 2011 the underground workings, and along trend west north-west (Monitor prospect), and east south-east (Goanna prospect). The company has been active in promoting some high grade discoveries, but no active mining has been seen at the time of writing.

Other Regions, Features and Areas containing this locality

References