The Otter Juan Mine is Kambalda's oldest producing mine and by far its largest single ore deposit. The mine has been in near-continuous operation since 1970 and to end-December 2010 had produced approximately 8.73 million tonnes of ore at an average grade of 3.58% nickel, for over 313,000 tonnes of nickel metal. Mincor acquired the Otter Juan Mine in July 2007 through its acquisition of the privately owned company, GMM Pty Ltd.
Otter Juan is an owner-mining operation and is operated by a skilled residential workforce of Mincor employees. The mine is now nearing the end of its life, and while profitable mining continues at low production rates, it is expected to close during the 2013 financial year.