Eldorado Gold Mine, Tennant Creek, Barkly Region, Northern Territory, Australiai

Regional Level Types
Eldorado Gold Mine	Mine
Tennant Creek	Creek
Barkly Region	Region
Northern Territory	Territory
Australia	Country

During it operating years from 1935 to 1958, the Eldorado was the richest gold mine in the Tennant Creek district. Young Englishman Jack Shaw with Charles Richards and Taff James had trekked down from Darwin, and discovered the deposit in 1932. Shortly after in 1936 they sold the mine to Central Australian Mines Limited for 150 000 pounds, making them instantly rich by the standards of the day.

In turn they sold the mine in 1939 to the newly formed
Eldorado Tennant Creek Pty Ltd. A battery was installed in 1940, and it was the only mine in the district allowed to work during the Federal Government mining embargo during World War Two, albeit at reduced rates due to a lack of labour. After the war, production ramped up with healthy profits, and dividends most years. The mine closed in 1958, due to poor gold values, throwing 53 men out of work.

A small open cut was developed in the early 1990's in what has since been termed Eldorado Shallows, rather than the old shaft as Eldorado Deeps. The mine has produced 216 000 tonnes of ore at 20.2 g/t Au.

Eldorado is a quartz-hematite lode, with little magnetite in the upper levels, and even less copper, but rich in gold. Much of the hematite is specularite. The ore body plunges steeply north-east, striking south-east, on the northern limb of an anticline.

The deposit is sited in a dilatant jog formed during D1 reverse faulting with hematite, magnetite, quartz, chlorite and muscovite replacing the sedimentary rocks, and infilling the jog, with stringers zones formed laterally and at depth below the ironstone.

The country rock is siltstone, shale and greywacke. The Thomas Fault roughly forms the footwall of the ironstone body. The massive ironstone grades to stringers at depth of martite-specularite-magnetite vein
networks. The veins are squiggly in places. Muscovite flakes are found in the veinlets, and as clots up to 5 mms wide.

Gold is found partly in ironstone and the breccia stringer zone, as visible gold flakes up to 1 mm in diameter on fracture surfaces in the kaolin-quartz-hematite veins zone, and more rarely within the veinlets. These veins are cut by sparse chlorite-quartz veins up to 30 cms wide.

There is an extension to the deposit under the Turner Fault (named after Sydney engineer W.J. Turner who worked at the mine in the 1930's), amounting to 29 200 tonnes of ore at 20.8 g/t Au (with a 3 g/t cut-off). Several hundred g/t values are not uncommon over distances of one metre.

At deeper levels is hematite-martite-magnetite-quartz-chlorite ironstone with a martite-magnetite-hematite stringer zone in chlorite-muscovite altered sedimentary rocks, breccia, and less altered greywacke, siltstone, and shale.

Found at the mine is cuprobismutite, sulphosalt hodrusite, and at the time of the source an un-named mineral being the most common sulphosalt at Eldorado as a Bi-Se-Cu mineral between guanajuatite and hodrusite. Minor chalcopyrite, digenite/neodigenite in emplecite, and the above species is also found in the 'deeps' area. Bi sulphosalts are interstitial to specularite, and inclusions within hematite, or intergrown with muscovite. These species are sometimes found in quartz veins with rare gold.

The mine is 4 kilometres south of Tennant Creek along the Stuart Highway, and one kilometre east of the highway. It is sited on the crest of an east-west ridge containing a line of several historic mines. Patties/Enterprise mines are to the west, and Cat Whiskers mine to the east. An open pit from the early 1990's, several large rusting tanks, and minor building ruins are at the site.

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References