The Geology and Ore Deposits of Gunpowder Copper Mine

Abstract

The Gunpowder Mine is located in North Western Queensland, Australia and has been developed by underground trackless method in a joint venture form of Consolidated Gold Fields Australia and Mitsubishi Group since October, 1971.
To date the mine has produced about one million tons of ore containing 2.8 percent copper, all of which have been shipped to Japan as copper concentrates.
The area around the mine is underlain by Lower Proterozoic sedimentary rocks; Eastern Creek Volcanics, Myally Beds, Gunpowder Creek Formation and Paradise Creek Formation.
Gunpowder Mine consists of three major deposits; Mammoth deposit, Esperanza deposit and Mount Oxide deposit. The host rocks of these deposits are quartzite and sandstone of Myally Beds (Mammoth), siltstone and shale of Gunpowder Creek Formation (Mount Oxide) and chert and siltstone of Paradise Creek Formation (Esperanza).
Mammoth deposit is now under production and the mine is subdivided into three major orebodies as No.1, No.2 and No.3 orebody.
Ore reserves of the Gunpowder Mine have successfully been increased to 10 million tons with an average grade of more than 3 percent copper after three years' integrated explora-tion work by Gold Fields and Mitsubishi.
The Mammoth ores are mainly composed of chalcocite, bornite, pyrite and chalcopyrite. Oxidation has taken place to 100 meters below surface and chalcocite occurs as deeply as 500 meters below surface. The mineralization should be more studied in relation to regional geological setting, structure including local faulting and brecciation and supergene process.