The Jundee-Nimary gold is hosted within a 4km (long) and 2.5km (wide) sequence of Achaean basalts and weakly differentiated dolerite sills separated by sedimentary rocks (carbonaceous shales, cherts, and siltstone) and dacitic porphyries. Younger felsic and intermediate porphyries and dolerite dykes intrude the sequence. The mine sequence is bounded to the west by a thick succession of felsic volcanics and volcaniclastics, and mineralisation diminishes eastwards as the mafic package becomes more magnesium–rich to ultramafic in composition.

The age of the gold mineralisation is approximately 2,700 million years (Archaean), and is controlled by a series of complex brittle fractures. Over 70% of the gold is hosted within the more brittle dolerite units with the remaining 30% associated with the basalts. The field has undergone multiphase deformation – folds, thrusts, strike and oblique slip faults. The gold is hosted within narrow, discontinuous quartz +/- carbonate veins (typically <0.5m wide) which contain abundant visible gold.

Low grade mineralisation occurred with the first phase of faulting. This was followed by the emplacement of large dacitic intrusions which locked up the initial fault lines causing some abutment pressure – during the second faulting phase this abutment pressure prevented the faults from slipping as easily as before causing a “ripping” between the two fault lines fracturing the rock and causing a relatively large low pressure zone ........

The Jundee operations currently consists of underground and open pit feed sources and a processing plant.

Three underground portals are in use which provide access to the various underground lode structures, namely the Barton, Gateway and Invicta portals. The Barton portal contains three active ore bodies (Nim3, Lyons and Westside) with development access well advanced in the Armada lode, whilst Invicta consists of the Invicta (remnants), Cardassian, Wilson and Deakin ore bodies. Gateway and Gringotts ore bodies are both mined via the Gateway portal, again with development access well advanced in the Revelation and Nexus lodes. Recent exploration has uncovered a new prospective mining area at depth (Zodiac).

The mining process is a geological driven model and production intensive due to the narrow vein nature and lithology of the ore bodies. There is a necessity for controlled mining practices to minimise the amount of waste dilution incurred during the ore extraction process. In general, the ore is mined using top-down long-hole (uphole) open stope bench retreat mining. The benches are nominally 20m apart (vertically). The lode structures have a dip of between 35-70 degrees and have multiple orientations. The mining method typically extracts the ore in 30-50m panels separated by 5-10m rib pillars which remain in-situ to provide geo-mechanical stability and support. For ore structures that dip between 25.0 degrees and 35.0 degrees the ore is extracted u ........

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The Jundee processing circuit is a conventional CIL plant with a hard rock processing capacity of approximately 3.0M tonnes per year.

The Jundee mill feed contains sufficient coarse gold to support the inclusion of a gravity concentration process in the milling circuit. The cyclone underflow product of up to four cyclones is diverted to a gravity circuit that comprises 2 x 30” Knelson concentrators. Approximately 40% of gold in the mill feed is recovered via the gravity circuit. The concentrate produced by the Knelson’s is fed to an in-line leach reactor (ILR) that uses a high concentration cyanide-caustic solution to rapidly leach the gold. Gold is recovered from this solution by means of an electro-winning process in the gold room.

The cyclone overflow slurry reports to the carbon-in-leach circuit for the processing of non-gravity recoverable gold. The circuit comprises two leach tanks and six adsorption tanks where the gold is leached into a solution and adsor ........