Mary Kathleen, Queensland

Mary Kathleen was a mining settlement in the northwestern part of Queensland, Australia. It is located in the Selwyn Range between Mount Isa and Cloncurry.

Mary Kathleen was first settled during the 1860s. Uranium was first discovered at Mary Kathleen by Clem Walton and Norm McConachy in 1954: the deposit and the township was named after the late wife of McConachy. Prospecting and exploitation rights were subsequently onsold, and in 1955 Rio Tinto Mining formed Mary Kathleen Uranium Ltd to develop a mine and service town. An architect-designed town grew during 1956-58, with reticulated water from a dam, Lake Corella.

In 1954, a significant uranium deposit was discovered at the site (20.7470°S, 140.0123°E). A sales contract with the United Kingdom Atomic Energy Authority was signed in 1956. Mining commenced at the end of 1956 and the treatment plant was commissioned in June 1958. The project was developed by Mary Kathleen Uranium Limited (MKU) at a cost of A $24 million. MKU was formed to develop the uranium deposits and work was soon commenced constructing the township, mine, and dam on the nearby Corella River. The ore was mined by the open-cut method and processed on site.

4,080 tonnes of uranium oxide being extracted between 1958 and 1963. In this first phase of operation from 1958 to 1963 Mary Kathleen treated 2.9 million tonnes of ore at an average grade of 0.13% to yield 4082 t (4500 short tons or 9 million pounds weight of U3O8) of uranium concentrate (then actually yellowcake - ammonium diuranate) containing 3460 tonnes of uranium. By 1963 the major supply contract had been satisfied ahead of schedule, and large reserves of ore lay at grass. Consequently, the works were closed down.

The mine then lay idle until 1974, when it was reopened. New supply contracts with Japanese, German and American power utilities prompted this re-opening, with Mary Kathleen's second life extended to 1982 when reserves were finally exhausted. The company made a share issue to raise capital, and the Commonwealth Government, through the Australian Atomic Energy Commission underwrote this, thereby obtaining a 42% holding in the company. Conzinc Riotinto of Australia Limited, a successor of Rio Tinto Mining, held 51%, and the public 7%. The second phase of production began in 1976 and the mine was finally closed down in 1982 after a further production of 4,802 tonnes of uranium oxide. A total of 31 million tonnes of ore were extracted from the mine until it was exhausted. Processing occurred on-site.

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