Mt Colin Mine (QLD)

The Mt Colin operation is a copper/gold mine approximately 50 km east of Mount Isa in North West Queensland, 100% owned by Round Oak.

The operation consists of an underground mine and surface infrastructure including contractor crushing facilities. 

Project location


The ore body was originally mined as an open pit which was completed in 2013 before mining transitioned to underground. Ore is crushed on site before being transported by road train to Glencore’s Ernest Henry facility north of Cloncurry where it is toll treated. 

Previously mined open pit above Mt Colin underground mine

The copper/gold ore is hosted in a steeply dipping lenticular skarn rock formation and extends over a length of around 250m at widths up to 12m. 

The mine uses conventional long hole open stoping with ore hauled to the surface in 60 tonne trucks. 

Mine development has reached a depth of approximately 430m from surface, with an expected final depth of 510m. The ore body remains open at depth with recent exploration drilling generating numerous high-grade intercepts down dip and along strike of the existing resource. 

Mine section view

The mine currently produces approximately 450,000 tonnes of ore each year, yielding approximately 10,000t of copper and 5,000 ozs of gold in some 50,000 tonnes of concentrate.

Since the start of underground operations in mid-2018, a total of approximately 650,000 tonnes of ore has been produced, with an average grade of 2.04% Cu and 0.39g/t Au, for total output of more than 13,000t of copper and 8,000 ounces of gold.

Underground mining is conducted by specialist underground mining contractor, Barminco. The mine site employs approximately 80 fly in/fly out workers who are accommodated on site in modern camp facilities.



The Mount Colin deposit lies within the eastern part of the Mount Isa lnlier, which has been the subject of extensive mining since 1867 and is host to world-class deposits including Cannington (Ag-Pb-Zn), Mount Isa (Cu, Ag-Pb-Zn), Century (Zn), Ernest Henry (Cu, Au), Osborne (Cu, Au), and Selwyn group (Cu-Au)

The Mount Colin shear-hosted Cu-Au deposit, hosted by the calc-silicates of the 1750-1740Ma Corella Formation and the 1740-1726Ma Burstall granite, is tabular, east-west striking, steeply north dipping with a true width of up to 10m+ and is open at depth at >500m below surface.

The mineral resource is largely fresh ore (chalcopyrite ore mineralogy) with oxide and supergene-classed mineralisation prevailing near surface.

Exploration drilling is currently being conducted from a dedicated hanging wall drill drive to identify additional ore stocks and extend the life of mine beyond 2025. 


The Mount Colin mineral deposit lies within the granted tenement ML 2640, which covers an area of 129.5 hectares, fully enclosing the project area.



Mt Colin was acquired in late 2012 when Round Oak’s parent company, Washington H Soul Pattinson, completed a takeover of Exco Resources, which had held the tenements since 2006. An initial resource was defined at Mt Colin in 1995.

Oxide ores at Mt Colin had initially been mined via small scale open pits until 2011. Round Oak’s predecessor company, CopperChem, resumed open pit mining in 2013 with plans to transition to underground mining in 2015, however, a combination of water shortages and falling copper prices caused the start of underground mining to be delayed until August 2018. First ore from underground operations was produced in September 2019.


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