The Ernest Henry iron oxide copper-gold deposit is located in the Cloncurry district within the Eastern Succession of the Mt Isa Inlier. The orebody is hosted within the Mt Fort Constantine volcanics, a sequence of intensely altered felsic to intermediate metavolcanics (dacite, andesite and basalt) and metasedimentary rocks that are Paleoproterozoic (1740Ma) in age. The orebody has no natural surface outcrop and lies beneath 50m of Phanerozoic cover comprising of clays, gravels and sands. The Ernest Henry deposit is a breccia pipe plunging approximately 45° to the south-southeast and is bounded between northeast trending ductile shear zones.

Copper and gold mineralisation occurs in a breccia comprised of strongly altered and replaced intermediate volcanic fragments in a matrix assemblage of predominantly magnetite, chalcopyrite and carbonate. Copper occurs as chalcopyrite and gold is strongly associated with chalcopyrite.

Economic mineralisation at E1 occurs as breccia-hosted mineralisation within the footwall volcanics at E1 North, and as strata bound, replacement style mineralisation within the mineralised sedimentary units at E1 North, Central, South and East.

Monakoff: As per 2015, Monakoff and Monakoff East remain excluded from the Ore Reserves. The expiry date of relevant tenements is 31 October 2032.

Economic mineralisation at Monakoff and Monakoff East occurs in very-fine to medium grained steeply dipping metasediment units.

The operation is an underground mining operation employing sub-level caving ore extraction method. There is also an underground primary crusher and ore handling system. Ore is brought to surface via a 1 km hoisting shaft with a hoisting capacity in excess of 6Mt ore p.a. The operation also has an effective and sophisticated above and below ground water management system.

Ore mined at Ernest Henry Mining is processed at on-site concentrator.

The concentrator incorporates grinding (four mills), conventional flotation and dewatering. A single copper-gold-silver concentrate is produced by a rougher and a three stage cleaning circuit. The Concentrate is treated at Glencore’s Mt Isa smelter (~150km trucking distance) and metal is refined at Glencore’s Townsville refinery.

The ore is crushed and ground in a series of mills before being mixed with water and various chemicals that help to liberate or separate the copper and gold from the remaining material.

During the flotation process, the minerals attach themselves to bubbles and float to the surface of the flotation cells where they are captured. This mineral-rich mixture is dewatered to form the final copper-gold concentrate.

The concentrator is a single line plant with an annual throughput capacity of 11 million tonnes of primary ore a year. It has the capacity to produce around 350,000 tonnes of concentrate annually.