Mt Isa is a well known mining region in Qld Australia.
The main metals mined are:
By the 1960s, Mount Isa was the hub of a lead, zinc, silver and copper supply network, including smelting, refining and recycling facilities in Europe.
The rich lodes at Mt Isa were not discovered until 1923 and were developed despite the remote location and harsh environment. The nearby, rich Hilton deposit was discovered in the late 1940s but not developed until the mid-1980s. Production at Mt Isa continues and it has been the second biggest lead producer in Australia. In the Mt Isa region, there are large mines at the George Fisher, Cannington and Century deposits, while the Dugald River and Lady Loretta deposits are yet to be mined. In the Northern Territory, the large McArthur River lead-zinc-silver deposit is a major producer.
Today, the 320km² Mount Isa lease encompasses not only the Isa operations but also the George Fisher mine. The ore mineralisation is stratiform, occurring in the 1,600 million-year-old Lower Proterozoic Urquhart Shale sequence. At Mount Isa, the sequence is 1km thick and dips at 65°. The orebodies lie within the upper 650m and are bounded by the Mount Isa fault on the west and by volcanic greenstones to the east. Comprising galena and sphalerite with pyrite and pyrrhotite, the lead-zinc-silver orebodies are concordant with carbonaceous dolomitic sediments, interfingering with the silica-dolomitic mass hosting copper. Over 20 ore zones are mineable, each up to 1.4km long by 800m deep and from 4m to 48m wide.
As of mid-2005, Xstrata reported that the underground Isa lead mine had proven reserves of 0.4Mt grading 5.9% zinc, 4.7% lead and 140g/t silver, and measured resources of 1Mt at approximately 7.3% Zn, 6.3% Pb and 180g/t Ag. The Black Star open-pit mine is based on reserves of 23.9Mt grading 5.1% zinc, 3.1% lead and 60g/t silver. Outside the Black Star project, the Mt Isa area has an open-pit mineable resource of 84.5Mt grading 4.1% zinc, 3.5% lead and 82g/t silver.