The Plutonic deposits are Archean Greenstone gold deposits. The gold mineralisation is predominantly structurally controlled occurring in a variety of stratigraphic settings, mainly associated with replacement-style lodes and stockwork veining within a wide variety of host rocks ranging from ultramafic and mafic volcanic rocks, metasediments, felsic intrusive, volcanoclastic units, and banded iron formations.

The Plutonic Marymia Greenstone Belt was initially interpreted as consisting of two parallel, northeast-trending mafic/ultramafic sequences, separated by a sedimentary/ conglomeratic unit in the centre. Recent re-logging and solid geological interpretation differs from the initial interpretation in that there are no mafic and ultramafic assemblages on the south-eastern edge of the Belt. The northwestern edge of the Belt consists of amphibolitefacies metamorphosed and foliated assemblages of ultramafic rocks, tholeiitic basalt, BIF, chert, felsic tuff, arkose and pelite. The central and southern part of the greenstone belt consists of metamorphosed boulder conglomerate with sub-rounded clasts of monzogranite, BIF and mafic schist in a foliated mafic matrix. The conglomerate is interlayered with arkose and rhyodacitic volcanic rocks, quartzite, pelite and amphibolite. Proterozoic dolerite dykes intrude the greenstones and the surrounding granites.

The structurally lowest known unit in the Plutonic Gold Mine stratigraphy is the Lower Basal Mafics unit, a banded garnetiferous carbonate-altered amphibolite, possibly derived from mafic sediments. Overlying the Lower Basal Mafic unit is the Basal Sediment unit, a sequence of metasediments of varying thickness, comprised of garnetiferous siltstone and minor graphitic shale. This unit is overlain by the Upper Basal Mafic unit, of similar character to the Lower Basal Mafic, which is, in turn overlain by the Footwall Ultramafic unit, a downward-facing komatiite sequence. The Mine Mafic unit overlies the Footwall Ultramafic unit and is the host lithology for the Plutonic Gold Mine deposit and consists of a sequence of fine to medium grained amp hibolites with relict pillow textures and narrow graphitic shale marker horizons. Detailed geochemistry of the Mine Mafic unit reveals a series of more primitive rocks at the top of the unit transitioning into low-K high-Fe tholeiites of more evolved parentage at the base, suggesting overturning of the unit. The Mine Mafic unit is comprised of multiple volcanic flows, separated into two sub units, the mineralised Upper Mine Mafic unit dominated by a coarse hornblende-rich high-Mg amphibolite at the top with intercalated high-Fe tholeiites, underlain by multiple volcanic flows of the Lower Mine Mafic unit comprised of only high-Fe tholeiites. The Mine Mafic unit is in turn overlain by the Hangingwall Ultramafic unit, a second sequence of downward facing komat iites. Studies of multiple komatiite flows within the Hangingwall and Footwall Ultramafic units indicate that both young downward and that the entire sequence is overturned.

Geological structures at Plutonic Gold Mine can be separated into two broad categories: low-angle thrusts and high-angle faults, based on orientation, deformation character, alteration assemblage and sense of movement. Within the Mine Mafic unit, the dominant fabric runs sub-parallel to the mineralised lodes and lithological contacts and is locally overprinted by younger penetrative fabrics, cutting and folding the layer parallel fabric, lodes and lithological contacts. The overprinting fabric(s) is present as a crenulation cleavage and tension gashes developed across the layer-parallel fabric and is best observed where it cuts across high-grade replacement lodes.

The main style of gold mineralisation (Plutonic brown-lode) typically occurs as thin (~1 - 3 m wide) lodes that consist predominantly of quartz-biotite-amphibole-titanite-epidote-carbonate tourmaline-arsenopyritepyrrhotite ± chalcopyrite ± scheelite ± gold. Visible gold is considered to have occurred at a late-stage during the evolution of the deposit as it is largely undeformed and overprints most, if not all, of the minerals and fabrics. It is typically associated with thin, discontinuous quartz-calc-silicate veins within the brown-lodes. Where these gold-bearing zones are well developed, they tend to be near-parallel to the stratigraphy as marked by the rare metasedimentary horizons and to the dominant foliation, which is also typically parallel to metasediment horizons. Geochemistry suggests that these lodes developed on the boundary between mafic units or are focused along or adjacent to minor metasedimentary units within the Mine Mafic unit. Lodes may be rich in arsenopyrite or pyrrhotite, and while arsenopyrite is a good indicator of mineralisation, it may not be present in all mineralisation.

The open cut pit limits were identified in order estimate the potential mineable quantities of plant feed and understand the characteristics and sensitivity of the potential to open cut mining.

Based on the selected mining method and 100 tonne excavators used for ore, RPM assumed an ore overall loss of 5% and waste rock dilution of 15%. Whittle 4X software assumes the grade of the dilutant rock to be zero.

The pit wall design criteria is based on historically applied criteria for the Main Pit for oxide and transition material, and an increase for the fresh zone (from a batter angle of 60 degrees (historical) to 70 degrees). The mine design parameters were confirmed as appropriate by the Plutonic mine geotechnical engineer, with appropriate controls for local batter scale failures. The recommended criteria were:

• Inter-ramp pit slope angles of 41-50 degrees, inclusive of berms;
• Bench height of 18 m (and 16 m above the 1496 RL);
• Berm width of 7 m for fresh (1424 bench and below) and transition (1460 bench and below) and 5 m for oxide; and
• Batter angle of 70 degrees for fresh rock, 55 degrees for transition rock and 50 degrees for oxide rock.

The main pit design makes use of the existing access into the pit on fill, so final ramps do not appear to be required for the east wall cut-back, except for the lower pit RLs. Note that the slope parameters used are the same as the 2007 Barrick Mining Study report, except for the increase in slope angle in fresh material from 60 degrees to 70 degrees. The overall slope angle for the main east pit cut-back is approximately 49 degrees and the pit depth between 150 and 300 metres.

The PP1 crushing circuit has a nameplate capacity of 2.5 Mtpa and consists of three stages of crushing:
- A 60 x 48 Jacques primary double-toggle jaw crusher,
- A Symons 7’ SXHD secondary standard head cone crusher, and
- Two Symons 7’ SXHD tertiary short-head cone crushers.
In addition, there are separate surge bins that are operated in closed circuit with two Nordberg 7.1 m x 2.4 m double deck vibrating banana screens. Crushed ore exits the pro duct screen with a top size of 10 mm and is stored in the fine ore bin.

Crushed ore is withdrawn from the Fine Ore Bin via two belt feeders (CV 14/15), which transfer ore onto the mill feed conveyor (CV04) that feeds into the primary grinding mill (ML01). The grinding circuit comprises a Svenson 4.5m diameter by 5.63m long primary mill and two Svenson 4.2m diameter by 5.63m long secondary ball mills. The primary mill has a grate discharge and is rubber lined. Its speed is fixed at 14.6 rev/min (72 per cent of critical) and the installed power is 1,600kW (1,350kW drawn). 78mm diameter forged steel grinding media is used in the primary mill.

The secondary mills are rubber lined overflow mills run at 15.8 rev/min (75% of critical), also with 1,600 kW power (1,450 kW drawn). The grinding circuit throughput is currently operated at 165 tph with a primary mill and one ball mill configuration; this however can be increased to 230 tph by running the stand-by ball mill. 40 mm High Chromium steel grinding media is used in the secondary mills.

To achieve increased capacity in the PP1 processing circuit to 2 Mtpa, the following is required:
- Crushing circuit : sufficient installed capacity; no upgrade envisioned; minor change in operating conditions (finer crush size : F80 of 5.0mm compared to current F80 5.5mm);
- Milling circuit : increasing of the size of motors on the SAG and two ball mills as well as upgrading the classification circuit;

The current PP1 plant throughput limit is ~1.8 Mtpa.

The strategic analysis selected Scenario 3 as the preferred development option as it is likely to generate the best cash flow as it reduces the plant operating costs by over 10% and increases throughput by 10%, for a low capital investment. Scenario 3 involves upgrading PP1 to process 2.0 Mtpa, comprising 1.2 Mtpa from the proposed open cut and 0.8 Mtpa from the underground mine.

The ore treatment process through the PP1 plant involves the following activities:
- Crushing and Grinding;
- Leach/Adsorption;
- Carbon Stripping/Elution/Electrowinning;
- Carbon Regeneration;
- Tailings Disposal;
- Reagent Mixing/Handling, and
- Plant Services.

To achieve increased capacity in the PP1 processing circuit to 2 Mtpa, the following is required:
- Leaching circuit : additional leaching capacity required to maintain 24 hour residence time, namely refurbish 3 PP2 leach tanks ........