The characteristics of the gold deposits at Higginsville are consistent with the greenstone-hosted quartz-carbonate vein (mesothermal) gold deposit model.

Throughout the Higginsville Gold Operations, a significant proportion of gold deposits are hosted by sediments within Southern Palaeochannel networks. Mineralised zones comprise both placer gold, normally near the base of the channel-fill sequences, and chemically-precipitated secondary gold within the channel-fill materials and underlying saprolite. These gold concentrations commonly overlie, or are adjacent to, primary mineralised zones within Archaean bedrock. Outcrop is generally poor, due to extensive ferruginisation, calcareous soils, aeolian sands and extensive areas of remnant lacustrine and fluvial sediments. The result is a complex, layered regolith, with considerable chemical re-mobilisation and re-deposition (Lintern et. al., 2001).

Higginsville is located almost entirely within the well-mineralised Archean Kalgoorlie Terrane, between the gold mining centres of Norseman and Saint Ives. The Archaean stratigraphy has a general northward trend comprising multiply deformed ultramafic – gabbro – basalt successions adjoined by sediments to the west and east. Shearing and faulted contacts are common. The units have been structurally repeated by east over west thrust faulting.

The HGO can be sub-divided into six major geological domains:
- Trident line-of-lode;
- Chalice;
- Lake Cowan;
- Southern palaeochannels;
- Mount Henry;
- Polar Bear Group; and
- Spargos Project Area.

Trident line-of-lode
The majority of mineralisation projects along the Trident line-of-lode are hosted within the Poseidon Gabbro and high-MgO dyke complexes in the south. The Poseidon Gabbro is a thick, weakly- differentiated gabbroic sill (Newman et. al., 2005), which strikes north south and dips 60° to the east, is over 500m thick and 2.5km long. The gabbro is broadly zoned (Zones 1 - 5), with Zone 3 considered the most favourable for mineralisation:
- Zone 1 is interpreted as an ultramafic cumulate base;
- Zone 2 is a feldspar-phyric mafic unit;
- Zone 3 is an equigranular, feldspar-quartz phyric unit.
- Zone 4 is a bladed amphibole unit; and
- Zone 5 is an equigranular, feldspar-amphibole phyric unit.

Chalice
The Chalice deposit is located within a north south trending, 2-3km wide greenstone terrane, flanked on the west calc-alkaline granitic rocks of the Boorabin Batholith and to the east by the Pioneer Dome Batholith. The mafic-ultramafic rocks of the greenstone terrane comprise upper greenschist to middle amphibolite facies metamorphosed, high-magnesium basalt, minor komatiite units and interflow clastic sedimentary rocks intruded by a complex network of multigenerational granite, pegmatite and porphyry bodies.

The dominant unit that hosts gold mineralisation is a fine grained, weak to strongly foliated amphibole-plagioclase amphibolite, with a typically lepidoblastic (mineralogically aligned and banded) texture. It is west-dipping and generally steep, approximately 60°-75°. It is typically more competent than the ultramafic unit.

Lake Cowan
The area is situated near the centre of a regional anticline between the Zuleika and Lefroy faults, with the local geology of the area made more complex by the intrusion of the massive Proterozoic Binneringie dyke.

The Binneringie dyke varies locally from a hornblende dominated dolerite to a feldspar dominated granodiorite, is medium to coarse grained, and is complexly interrelated to the mineralised structures in the Lake Cowan area. In a break of form for these generally east-northeast – west-southwest trending dyke systems, at Lake Cowan the Binneringie dyke follows the deep seated crustal weaknesses north and south for some distance, in the process interfering with the pre- existing mineralisation on a large scale. The majority of mineralisation at the Lake Cowan Mining Centre is hosted within an enclave of Archaean material surrounded by the Binneringie dyke.

Southern Palaeochannels
Throughout the Higginsville Gold Operations, a significant proportion of gold deposits are hosted by sediments within the Southern Palaeochannel network (Figure 7-21). Mineralised zones comprise both placer gold, normally near the base of the channel-fill sequences, and chemicallyprecipitated secondary gold within the channel-fill materials and underlying saprolite. These gold concentrations commonly overlie, or are adjacent to, primary mineralised zones within
Archaean bedrock.

Polar Bear Group
The geology at Polar Bear is dominated by complexly deformed Achaean greenstone assemblages of the Norseman-Wiluna Greenstone Belt which have been metamorphosed to upper greenschist facies. The major regional structures in the area are the Boulder-Lefroy Fault, located approximately 10km northeast of the project area, the Mission Fault located in the southern portion of the package, and the Black Knob Fault that transects the central portion of the project.

Spargos Project Area
The Spargos Project occurs within Coolgardie Domain of the Kalgoorlie Terrane. The western boundary of the Domain is marked by the Ida Fault, a crustal-scale suture that separates the eastern goldfields from older terranes to the west. Its eastern margin is marked by the Zuleika Fault. The geological setting comprises tightly-folded north-south striking ultramafic and mafic volcanic rocks at the northern closure Widgiemooltha Dome.

There are six (economically viable) open pit operations planned for the Higginsville Central deposits, all followed the industry standard approach for developing an open pit drill, blast, loading by excavator and transported by haul truck mine planning approach.

The mining method for these open pits are drill, blast loading by excavator and trucking the waste rock to a dedicated waste rock dump area close to the pit and ore trucked to a local pit stockpile or directly trucked to the Higginsville processing plant.

Mining will take place in benches with flitch loading (on either 2.5 m or 3 m high flitches). The open pit operations require diligent ore control/grade control procedures and resources. When ore drilling and blasting is performed, the drilling chips are assayed and in combination with the planning block model, zones within the ore bench is demarcated (by coloured tape/spray or a combination of the two) to define if a parcel of ore is low grade, medium or high-grade.

The post loading grade control process is just as important, to ensure the reconciliation is inline with planning and to ensure ore modifying factors are reasonable and follow due process.

The typical open pit mining cycle involves:

- Demarcation (on each bench level) of ore/waste and low-grade zones;
- RC drilling (grade control drilling prior to mining to refine/update waste/ore zones);
- Bench drilling floor preparation and survey depths for each blast hole (depth/lengths of each blast hole are key to ensure bench floor controls);
- Drilling of blast hole;
- Review and QA/QC of blast holes to ensure they are drilled to design;
- Re-drilling of any holes not deemed correct/appropriate;
- Charging and firing of blast holes;
- Loading of the heave;
- Loading of the flitches, loading to be supervised in ore blocks to ensure correct truck destinations; and
- Trucks haul ore to either a lower grade stockpile close to the open pit or directly to the Higginsville processing plant.

Currently, Karora is mining from two open pits at Higginsville: the Baloo and Fairplay North open pit mines.

Mount Henry
The Mount Henry mining study adopted a conventional truck and shovel open pit mining methods.

The study assumes that all mining related operations will be undertaken by a suitably qualified and experienced mining contractor.

The current mine plan assumes:
- the mining of the ore zone is planned at a nominal 5 m bench height using a back-hoe excavator mining on two 2.5 m flitches. This will facilitate selective mining between ROM grade ore, potential low-grade ore and waste boundaries;
- waste will be blasted on 10 m benches where possible, typically in continuous waste zones from the HW of the pit to the HW edge of the ore zone;
- grade control will be based on an advanced RC grade control program in 20m – 30m vertical campaigns across the various working areas; and
- wherever possible blasting will consist of either separate waste and ore blasts to free faces parallel to the deposit, or the ore will be chock blasted within the waste zones to minimise excessive dilution of ore, or loss of ore to waste.

Chalice
The mine planning of Chalice (underground only) considered top down, mechanised long hole retreat stoping (LHOS). The Current LHOS stope design dimensions are 20 to 25 m high (following the typical historic level spacings) and vary in width from 4.5 m to 6 m with 15 m stope strike lengths (15 m strike lengths will ensure excellent stope dilution control).

Chalice will develop good continuous and larger stopes, with reduced development metres (low development meters to ore tonnes ratio). Chalice is also a low-grade underground design and require higher volumes/tonnages to make the project marginally economical. The mine planning and production scheduling for the Chalice design targeted between 40 kt and 50 kt of ore monthly.

The processing plant consists of an open circuit jaw crusher followed by closed circuit secondary and tertiary crushers, a fine ore bin and ball mill.

Mill feed is trucked to the run of mine (“ROM”) pad from open pits in the immediate Higginsville area together with underground ore from the Beta Hunt mine located 73km to the north. The mill feed is classified and stockpiled according to gold grade to blend an optimal feed mix to the processing facility. Oversize mill feed is sorted from stockpiles and broken on the ROM pad using a loader or excavator. Any oversize that cannot pass through the primary crusher grizzly is broken by a rock breaker.

The crushing circuit has a nameplate capacity of 1.0 Mtpa and consists of four stages of crushing:
- A 36 x 48 Jacques primary single-toggle jaw crusher;
- A 1.68 m Trio Turbocone TC66 (standard configuration) secondary cone crusher;
- A 1.68 m Trio Turbocone TC66 (short head configuration) tertiary cone crusher; and
- A 1.29 m Trio Turbocone T51 quaternary cone crusher.

Crushed material exits the product screen with a P80 of 10mm and is stored in the fine ore bin. The fine ore bin has a live capacity of 1,500t.

Crushed mill feed is withdrawn from the Fine Ore Bin via a belt feeder, which transfers the crushed product onto the mill feed conveyor that feeds into the ball mill. Mill feed can also be fed via an emergency feeder which is fed from the fine ore stockpile via FEL.

The grinding circuit consists of an overflow ball mill, hydro-cyclone cluster classifier and gravity recovery circuit. The ball mill is a LMMP/CITIC-HMC 4.90 m diameter by 6.77 m EGL overflow ball mill.

The crushed mill feed is conveyed to the ball mill feed chute and combined with process water and recirculating cyclone underflow slurry. The ball mill operates in closed circuit with the mill discharge slurry classified by a cluster of hydro-cyclones.

Oversize ore particles and reject grinding balls are rejected from the ball mill discharge slurry by a 16 mm aperture trommel screen connected to the discharge trunnion of the mill. The oversize material (mill scats) is removed from the circuit to protect the cyclone feed slurry pumps and reduce wear rate on cyclone liners and the slurry handling equipment. Mill scats are rejected to a scats bin for removal by wheel loader.

The processing plant consists of an open circuit jaw crusher followed by closed circuit secondary and tertiary crushers, a fine ore bin, ball mill, gravity separation circuit, one leach tank, and six carbon adsorption tanks.

The primary sections of the processing plant that are currently in use are:
- Crushing and conveying;
- Ore storage & reclaim and grinding;
- Leaching and carbon adsorption;
- Carbon stripping, electrowinning, refining and carbon re-generation;
- Tailings thickening;
- Tailings deposition and storage;
- Reagent mixing and handling; and
- Plant services.

Gravity and Intensive Cyanidation
A gravity separation circuit is included in the design to enhance the recovery of gold that concentrates in the hydro-cyclone underflow stream.

A 100 t/h bleed of the hydro-cyclone underflow stream is delivered to the gravity feed screen for classification. The gravity feed screen is a 1.2m wide b ........