Moline Mine (Moline Dam; Eureka; Hercules-Eureka; Northern Hercules; Southern Hercules), Pine Creek, Victoria-Daly Region, Northern Territory, Australiai

Regional Level Types
Moline Mine (Moline Dam; Eureka; Hercules-Eureka; Northern Hercules; Southern Hercules)	Mine
Pine Creek	Creek
Victoria-Daly Region	Region
Northern Territory	Territory
Australia	Country

Gold Mine 50 kilometres east north-east of Pine Creek, just south of the Kakadu Highway, and about 15 kilometres before the Mary River Roadhouse. A number of historic mines exist south of the Moline Mine.

The deposit was discovered and worked by Chinese miners from 1882. Historical information for the period is lacking, and may reflect the mine remained in the hands of individuals or worked on an intermittent basis. It is stated that getting payable gold from the deposit became increasingly difficult.

The De Bernales Group investigated the mine from 1935-1937. De Bernales was a London based entrepreneur, who was raising funds to develop mainly Western Australian mines. There was never a shortage of hype when De Bernales was around. Glowing reports were published, and statements the ore presented no metallurgical problems, which was simply not true. At this time it is known as the Hercules-Eureka Mine. The mine laid idle between 1937 to 1954.

Northern Hercules NL was formed in 1954 to develop the mine. Much money was spent erecting a treatment plant. Delays were caused by the wet season, and the company lost money when a contractor failed to undertake construction work at the site. A request for more shareholder money, downgrades in likely gold production, and disputes over perceived favouritism in share allocation, led to a shareholder revolt. In late 1956 the board was replaced and the mine closed.

A largely unused treatment plant here drew the attention of uranium miners at the South Alligator field, 50 kilometres to the east south-east. United Uranium NL purchased the plant in 1961, renaming it Moline, and trucked ore to the plant from several small uranium mines until 1964. In the early 1970's, the plant was used to treat copper ore from the Mount Diamond Mine to the south.

At this point there was discontinuous workings to 90 metres below the surface, with historic stopes less than 2 metres wide, centred on narrow quartz-pyrite vein mineralisation.

In the early 1980's, the site was explored again, and substantial mining took place. Major open pits were developed named Northern Hercules, School, Four, Moline and Tumbling Dice, with sixteen smaller satellite pits confined to the oxide zone. Northern Hercules and Moline pits were 60-70 metres deep, and produced most of the ore.

There was more open pit mining in 1987, and the tailings were re-treated. Mine Management Pty Ltd recovered 38 257 ounces of gold across 1988-1991, but the mine closed due to metallurgical problems treating the oxidised refractory gold mineralisation. Later the Commonwealth Government trucked in tailings from the uranium mines along the South Alligator River valley, combined this with the Moline tailings and encased the whole lot in earth.

The geology of the deposit is complex and has provided a headache for miners trying to extract the gold.

The Moline Dam deposit occurs near the top of the 200 metre thick Mt Bonnie Formation, the upper most unit of the East Alligator Group. The Northern Hercules deposit is at the same location, but higher within the Burrell Creek Formation of the Finniss Group.

It is hosted by an 18 kilometre long anticlinorial structure that has suffered several phases of folding, faulting and shearing, which has influenced the placement of gold.

At Moline Dam the gold is hosted by banded iron formations, chert, silicified slate and quartz veins. Gold is associated with banded and network veined pyrite-pyrrhotite, sphalerite, galena, arsenopyrite and bismuthinite, in micro and macro folded, disrupted, laminated chert, banded iron formation, and shale. This is variably sericitic, carbonaceous, siliceous, chloritic, feldspar-albite-adularia, tourmaline altered, and pyritic/pyrrhotitic. Sulphides vary from finely disseminated, coarse, and layered in quartz-albite gangue. The gold is present in four lodes up to 23 metres wide each, 30-100 metres below the surface, and strike 1100 metres.

The Northern Hercules mineralisation is associated with a steeply dipping quartz-pyrite-arsenopyrite, chalcopyrite, sphalerite, galena veining in multiple sub-parallel lodes. These cut the sandstone-greywacke-siltstone-shale host sequence, cutting obliquely for an 800 metre strike, with four lodes up to 23 metres wide each.

The Southern Hercules deposit is a continuation of the Northern Hercules deposit, but is hosted by the Mt Bonnie Formation, and is similar to that described for Moline Dam.

In theory this should have produced interesting and varied specimens, but at the time of writing only olivine photographs have been posted on Mindat. The encasement of the tailings in earth does not bode well for specimen collecting.

Other Regions, Features and Areas containing this locality

References