Guelb Moghrein mineralisation may be classed as a structurally modified iron ore copper gold (IOCG) deposit that is hosted in a coarse grained ferro-magnesian carbonate (FMC) unit. Copper and gold mineralisation is largely coincident with some evidence for elevated gold in the shallow mined out upper zones. The main sulphide minerals are chalcopyrite and pyrrhotite with magnetite becoming more abundant external to the sulphide bodies. The zones of mineralisation were strongly controlled by tectonic shearing and faulting which resulted in topographic expressions of the deposit in the form of two hills known as the Occidental and Oriental hills. Mineralisation below Occidental hill is considerably larger than that at Oriental, and dips by about 20 degrees to the south with a strike length close to 700 m and a dip extent of close to 1,000 m. The Occidental mineralised vertical width varies according to structural controls and ranges from a few meters to several 10’s of metres. The mineralisation below Oriental hill is limited to the shallow outcropping area of the hill and has an ellipsoid shape with a strike length of around 250 m and a width of about 100 m.

The FMC unit is the primary host of Guelb mineralisation and is comprised mainly of chalcopyrite and pyrrhotite within the un-oxidised zone. Other minerals include iron-cobalt-nickel arsenides and bismuth-gold-silver-tellurides. Gold is largely coincident and associated with chalcopyrite.

A shallow (<40 m) oxidised zone has resulted from surface weathering and oxidation of the deposits primary sulphide mineralisation. Commonly, the oxidised zone has minerals such as native copper, malachite, cuprite and chalcocite. Mineralisation of the carbonate units is suggested to be hydrothermal and associated with the D2 deformation event, which was subsequently deformed by faulting and thrusting of the D3 event. The siderite within the FMC is considered to have provided a reactant for the hydrothermal Cu-Au bearing fluids. Sulphide mineralisation is often better developed along the basal portions of the FMC and ranges from semi-massive to disseminated.

The topographic expression of the Guelb Moghrein mineralisation outcrops as two small hills of notable FMC gossans. The two hills are known as Occidental and Oriental, below which mineralisation is located as two distinctly different volumes. Occidental is characterised as a tabular shaped body dipping to the south by approximately 20 degrees and has a strike length of 650 m and dip extent of 1200 m. The width of Occidental mineralisation ranges from a few meters to 10’s of meters. In contrast the Oriental deposit is much smaller and is restricted as an ellipsoid shaped body immediately below the Oriental hill. Oriental has a strike length of 500 m and is approximately 200 m wide.

Mining at Guelb Moghrein is carried out in a single open pit using hydraulic excavators and mechanical drive haul trucks.

Ore from the open pit mine and stockpiles is crushed, milled and then undergoes sulphide flotation to produce a copper-gold concentrate, which is shipped to offshore smelters (mainly in China).

Since commissioning, the Process plant capacity has been expanded from 2 Mtpa to 4 Mtpa with current management focussing on improving recoveries and costs.

The unit processes currently are:
• primary crushing and ore stockpiling
• grinding in a 5.8 MW SAG mill and 4 MW ball mill
• gravity recovery of gold within the ball milling circuit
• trash screening for fibre removal
• rougher flotation
• three stages of cleaner flotation, including regrind and column flotation
• gravity recovery of gold on reground cleaner concentrates
• dewatering of mixed flotation and gravity concentrates in a thickener and ceramic disc filters
• (recovery of high grade magnetite from flotation tailings) – currently not in operation
• dewatering o ........