MIM Holdings Limited was an Australian mining company created in 1970 as the parent company of Mount Isa Mines Limited, which operates the Mount Isa mines in north-west Queensland. Based in Brisbane, the capital city of the Australian state of Queensland, MIM Holdings owned and/or operated coal, gold, and base metal mines in Australia and Argentina. It also operated lead and copper smelters in Mount Isa, a copper refinery in Townsville (Queensland), a lead refinery at Northfleet (England), zinc smelters using the Imperial Smelting Process at the National Smelting Company located within Avonmouth Docks (England) and Duisburg (Germany), and a precious metals refinery in Sydney.
MIM Holdings was, for a brief period in 1980, Australia's largest company by stock market valuation.
MIM Holdings was responsible for several significant technological advances in the mining industry, including the Isa Process tank house technology, developed at its subsidiary Copper Refineries Pty Limited in Townsville, Queensland; the Bottom-blown oxygen converter ("BBOCTM") developed at its lead refining subsidiary, Britannia Refined Metals, at Northfleet in England; and the ISASMELT top-entry submerged lance smelting process, Jameson Cell flotation technology, and the IsaMill fine grinding technology, all developed at its Mount Isa Mines Limited operations in Mount Isa.
MIM Holdings was taken over by Xstrata for a total of US$2.96 billion (A$4.93 billion), including assumed debt, in 2003, and delisted from the Australian Stock Exchange on 30 June 2003. On 2 May 2013, Xstrata merged with Glencore to form Glencore Xstrata plc.