Our history

In February 1923 while travelling across Queensland’s dry Gulf Savannah, prospector John Campbell Miles happened upon one of the richest known zinc-lead seams in the world.

Miles’ discovery led to the establishment of one of Australia’s most iconic and enduring natural resources companies, Mount Isa Mines. It heralded the birth of a community that has prospered alongside our operations and remains central to our long-term success.

A highly mineralised environment

Miles became intrigued by what appeared to be mineralised outcrops by the banks of the Leichhardt River. Using a horse-shoeing hammer, he hacked off samples of dark coloured, unusually heavy stone and sent them to the Government assayer in Cloncurry. They were found to contain as much as 78% lead-silver.

Establishment of Mount Isa Mines

Over two months, Miles pegged out the ‘Racecourse’ lease in the area surrounding the outcrops. He named the larger outcrop ‘Mount Isa’, claiming 17 hectares that would become one of the most productive single mines in history.

On 16 January 1924, Mount Isa Mines Ltd was established—Australia’s most distant mine from a coalfield or seaport.

Weathering the Great Depression

The region weathered the Great Depression remarkably well. The mine provided consistent work for a thousand men throughout the 1930s while a quarter of the male population in major cities was plunged into unemployment and poverty.

By the late 1940s, workers at Mount Isa Mines could earn up to three times the average wage of men in Brisbane or Melbourne.

During the early years, the company focused on zinc-lead-silver production with a brief period of copper production in the 1940s to contribute to the nation’s World War II effort. Parallel production of zinc-lead-silver and copper did not begin until 1953.

A commodity expansion in the early 1950s saw another influx of people settle in Mount Isa. Many were post-war immigrants and, for them, Mount Isa became a beacon of hope, an opportunity to rebuild a world away from their war-ravaged European homelands.

With the pioneering spirit required to make the most of the opportunities the growing mining company presented, these new additions to Mount Isa's mining fraternity were welcomed with open arms. Their legacy is still seen in Mount Isa's rich and culturally diverse community today.

Revolutionising global mining and smelting processes

By 1955, Mount Isa Mines had become the largest mining company in Australia. In the following years, many new technologies were developed onsite that revolutionised mining and smelting processes all over the world.