The active Beaconsfield mine (Beaconsfield Gold Project) is centred on the old Tasmania Reef Mine which is located 40 kilometres by road north-west of Launceston, Tasmania.
The Tasmania Reef is a gold-bearing quartz-carbonate-sulphide vein occupying an old fault structure which transgresses a series of sedimentary beds. The reef at Beaconsfield is in many respects analogous to the gold-arsenic-quartz, dilational-fill mesothermal deposits of Central Victoria, particularly those at Ballarat and Bendigo. The Tasmania Reef has an average strike length of around 350 metres, an average horizontal thickness of approximately 3.1 metres and dips to the south at an average of around 60 degrees.
The underground mine was operated from 1877 for 37 years, during which time approximately 840,000 ounces of gold were produced from 1,070,000 tonnes of ore at an average mill recovered grade of 24.3 g/t gold. With an average mill recovery of around 85%, the average head grade of the ore, after mining dilution, would have been over 28 g/t gold, making Beaconsfield one of the richest gold mines in Australia at the time. The mine was worked to a maximum depth of 455 metres. Economic conditions and technical considerations, in particular the inefficient mine pumping methods available at that time, led to the cessation of mining at the outbreak of World War I in 1914 and the subsequent flooding of the shafts and workings.
Mining restarted in the 1990s.
The present day gold mine can be seen from a viewing platform at the Grubb Shaft Museum - Gold & Heritage.
Refs.:
http://www.beaconsfieldgold.com.au/BMJV.html
