Regionally the mineralisation is hosted within early Ordovician sediments as part of the
Girilambone metasedimaents. The Larsens mineralisation is hosted within with the Pelitic to Psammite sediments, and sparse zones of courser sandstones of the Girilambone Group.

The Larsens sulphide mineralisation is stratiform and is classified as a “Besshi style” volcanogenic massive sulphide. Mineralisation is dominated by massive pyrite – chalcopyrite, with minor banded to stringer pyrite – chalcopyrite, and sparse locally important magnetite chalcopyrite.

Structurally the Larsens sulphide mineralisation is hosted within a corridor of moderate to intense shearing related to a thrust fault observed in the east wall of the Eastern Shear of the Murrawombie Pit (Murrawombie pit is located approximately 4 km SW of the Larsens mineralisation). The shear corridor has been traced by Sirotem (geophysical exploration tool) to the north west of the Murrawombie pit, with the Larsens mineralisation sitting Hanging Wall to the Eastern Shear, in relatively un-deformed sediments.

Open pit mining of the near surface oxide portion of the Larsons deposit was completed prior to 2002 by the Girilambone Copper Company.

The mine plans assume the use of up-hole bench stoping with sub-level developed at 20m vertical intervals. Rib pillars are to be left in sub economic areas of mineralisation. There is no backfill required.

The crushing circuit comprises an ore bin with a fixed 800 mm aperture grizzly, feeding ore via a vibratory feeder to a Kemco S7N single toggle jaw crusher with a feed opening of 1.22 x 1.02 m.

Crushed ore of P80 100mm is conveyed to a 6,000 tonne stockpile where it is reclaimed via three vibrating feeders.

Grinding comprises an ANI Ruwolt fixed speed high aspect 6.7m dia X 2.13, 1500 kW SAG Mill, discharging via a trommel screen to the secondary grinding circuit. Lime is added at the SAG to target pH 10.5 for pyrite suppression.

Secondary grinding comprises a Marcy 3.81 m dia x 5.18 m 1250 kW ball mill operating in closed circuit with 500 mm dia Linatex hydrocyclones. Cyclone overflow discharges to two parallel Metso Vertimills (VTM800STD) installed as part of the TEP and shown in the foreground of the lower photo.

The grinding circuit produces a cyclone overflow product of P80 75 µm at 30 to 35% w/w solids.

The tertiary cyclone overflow feeds two 50 m³ Wemco tank cells (installed as part of the TEP) in series for primary rougher flotation.

Regrind is achieved by a 2.0 m dia x 3.4 m 150 kW ball mill in closed circuit with Cavex hydrocyclones. The underflow reports to regrind and overflow to scavenger cleaner, rougher cleaner and final conc.

The Tritton flotation circuit produces a copper concentrate typically with 25% Cu, <1 g/t gold and 30 g/t Ag from a mill feed of 2.1% Cu, 0.15 g/t Au and 6- 7 g/t Ag.

Copper is recovered by cementation from the residual acidic copper solutions circulating in the Girilambone heap leach pads.