The Sihayo gold belt, which hosts the Sihayo and Sambung gold resources, is a 15 km long NW-SW trending corridor of Permian calcareous volcano-sedimentary rocks and associated intrusions. These rocks are highly prospective for sediment-hosted gold, epithermal gold-silver veins, and porphyry-related gold and copper mineralisation. The Sihayo gold belt is located on fault strands from the western margin of the dextral transtensional jog in the TSFZ. The bulk of the gold resources at Sihayo and Sambung is hosted by a NW-SW striking, moderately NE-dipping package of Permian shallow marine fossiliferous limestones. The gold is generally submicron size and, unless weathered (oxidised), it is locked in disseminated fine-grained arsenian pyrite mineralisation in multiple stratabound replacement-style jasperoid lenses and discordant bodies within the karstified, hydrobrecciated and tectonised host rocks. The resources are classified as sediment-hosted gold (SHG) deposits.

The mineralised Permian limestones and volcaniclastic rocks are disconformably overlain by Tertiary siliciclastic sandstones and carbonaceous mudstones. Uplift and erosion have removed most of the caprock at Sambung, but about 70% of Sihayo is covered by Tertiary caprock, which is up to 150 m thick or more on the eastern side of the resource. Diorite intrudes the Permian rock package in dykes, sills and laccolith, and some of these intrusions extend across the disconformity into the Tertiary caprocks.

Karstification features are well-developed within the Permian limestones. The karst cavities commonly contain cave-fill sediments showing a large range of facies and sedimentary structures including finely laminated oxidised and carbonaceous muddy-silty sediments with dropstones, graded bedded sandy-gritty sediments, poorly-sorted matrix-supported polymictic breccias and fragment-supported monomictic shingle breccias. The cave-fill sediments are unconsolidated or show varying degrees of lithification caused by hydrothermal alteration and mineralisation. Breccia clasts and dropstones, including mixed carbonate and siliciclastic rock types, also show varying degrees of alteration and intra-clast veining.

An unconsolidated bouldery clay regolith (eluvial-colluvial overburden) overlies parts of the Sihayo and Sambung gold resources. This is locally mineralised with variably oxidised jasperoid boulders and detrital gold in the gritty clay matrix. The latter has been extensively worked by artisanal miners to about 5 m average depth over the Sambung resource area. The thickness of the regolith varies dramatically where influenced by the occurrence of sinkholes and other irregularities on the underlying karstified bedrock.

Mining method
- Conventional open pit mining using 40 t class shovels and 40 t class articulated dump trucks.
- Drill and blast will be required in transition and primary material only. Oxide ore is assumed to be 50% free dig. Oxide waste is assumed to be 30% free dig. 4m benches will be mined in 2m flitches to increase selectivity.
- The mine’s development is planned in several stages to enable lower stripping requirements at the start of the mine life and backfilling of mined-out pits.
- A network of pioneering roads will be built to access the two deposits and the necessary mining infrastructure; allowance in the mining costs and the number of mining equipment has been made to account for this task.

Pit design
- Optimum pit volume determined using GEOVIA Whittle TM computer software based on the mining models LG_SIH_3.dm for Sihayo and LG_SAM.dm for Sambung.
- The revenue factor 1 shells were selected for the Sihayo and Sambung deposits in order to maximize the mine life.
- Inferred Mineral Resources were considered as waste for pit optimization and economic evaluations.
- Pit staging limits between revenue factor 0.34 and revenue factor 1 were targeted to minimize stripping ratio and enable backfilling of mined-out pits with waste material.
- Pit designs developed in Datamine computer software using the pit optimization shells as a guide and based on the Measured and Indicated Mineral Resources only.
- Allowance of access ramps (8m single lane and 15.7 m dual lane) and minimum mining widths of 15 m is included in the pit designs along with the use of top loaded goodbye cuts.

The Project’s financial evaluation is based on a mining schedule developed by AMC Consultants. The schedule, estimates that 13.7 Mt of ore at an average stripping ratio of 4.4 is produced over the 8-year life-of-mine (LOM) for a total material movement of 73.5 Mt. The AMC schedule includes approximately 1.2 Mt of material not included in the Ore Reserve.

Approximately 0.8 Mt (5.6% of the LOM ore production) of the additional plant feed comes from material currently classified as Inferred Resources, and the balance is material from the Sihayo South satellite pit that was excluded as it requires further geotechnical investigation.

Waste mining will take place in two parts. The owner-operator mining fleet will excavate and dump waste as part of the ongoing ore mining operations. There will be an additional bulk waste removal program, undertaken by a mining contractor from the end of the 3 rd year of mining. The bulk program will remove approximately 22.5 Mt of waste that overlies the deeper part of the economic mineralisation in the southern part of the Sihayo pit and the Sihayo satellite deposit. This bulk mining exercise will focus on removing waste at the lowest cost over a 24 to 30 month period. No grade control will be required in the bulk waste removal program.

The processing plant is designed as a simple CIL circuit for a non-refractory ore. Although the plant has been designed around a hard-rock throughput of 1.5 Mtpa, the design allows up to 2 Mtpa of oxide and transitional ore to be treated. The processing plant layout is incorporates the following circuits:
- Crushing (jaw crusher)
- Milling (SAG mill and hydrocyclones)
- Classification
- Leaching
- Adsorption
- Elution
- Carbon regeneration
- Electrowinning
- Smelting
- Cyanide destruction
- Mercury/arsenic precipitation
- Tailings thickening
- Tailings disposal
- Water treatment
- Reagent mixing and supply services

The design includes the detoxification of the tailings prior to the slurry reporting to the tailings storage facility (TSF). This will be achieved by using proven technologies including cyanide destruction and precipitation of any leached mercury and arsenic to a stable soli ........