The Tropicana Gold Project area lies east of a northeast trending magnetic feature, interpreted to be the major tectonic suture between the Yilgarn Craton and the Proterozoic Albany-Fraser Orogen that extends over 700km. The gold deposit is hosted in Archaean gneissic metamorphic rocks (ca. 2,640Ma) with cover sequences generally 10 to 30m thick resulting in the mineral deposit not being exposed at surface.

The 5km long strike of gold mineralisation at Tropicana is subdivided into five shear offset zones from north to south – Boston Shaker, Tropicana, Havana, Havana Deeps, and Havana South. The mineralised corridor is ~1.2km wide and up to 1.5km down dip to the current deepest drill intercepts. Within each zone the gold mineralisation trends north to northeast. Gold is concentrated in ~2m to ~50m thick subparallel layers within the ‘favourable horizon’ which comprises quartz-feldspar gneiss units.

Together, the Tropicana, Havana, Havana South and Boston Shaker deposits define a northeast trending mineralised corridor, approximately 1.2km wide and 5km long that has been tested to a vertical depth of more than 1,200m. The Mineral Resource remains open down-dip from the Tropicana, Havana and Boston Shaker deposits and has the potential to be extended to the north and south. Neither the immediate metamorphic host rocks nor the mineralised zones are exposed at surface due to the presence of widespread younger cover sequences.

The Tropicana area is covered by a 10m to 30m thick unconformable cover of Permian and Tertiary sedimentary rocks that have Tertiary lateritic weathering. In some areas the cover sequence also includes Holocene aeolian sands and colluvium.

The Tropicana deposit comprises a mineralised zone up to 50m thick, hosted predominantly in quartzo feldspathic gneiss with a garnet-gneiss dominated hangingwall package. The mineralisation is comprised of subordinate thin (3 to 5m), discontinuous mineralised lenses that typically return intercepts of >0.5g/t gold. The Havana deposit comprises a lower, laterally continuous, higher-grade lode up to 50m thick that is overlain, in the central and southern parts of the pit, by stacked, typically lower-grade and thinner (up to 25m thick) mineralised zones. Havana is also dominantly hosted in quartzo-feldspathic gneiss, again with a garnet gneiss dominated hangingwall.

Mineralisation is accompanied by pyrite (2% to 8%) with accessory pyrrhotite, chalcopyrite and other minor sulphides and tellurides. The gold mineralisation is related to shear planes that postdate the main gneissic fabric developed during peak granulite-facies metamorphism.

Open pit mining activities are undertaken by Macmahon in an alliance partnership with AngloGold Ashanti. Mining is conventional open cut, drill and blast, followed by truck and excavator operation to develop the deposits (Havana, Havana South and Boston Shaker). The total annual movement of ore and waste is approximately 95Mtpa. Underground mining utilises mechanised jumbo development and open stoping methods. At peak production, annual production from underground is planned to reach 1.1Mt of ore.

Development of the Boston Shaker underground mine was approved in March 2019, and the mine transitioned into commercial production september 2020 on schedule.

Access to the mineralisation will be via a decline with a portal at the base of the Tropicana Open Pit. A second portal will be established later in the completed Boston Shaker Open pit. As disclosed in the Prefeasibility Study (PFS)1, underground conditions at Boston Shaker are good and conventional ground support systems and practices will be used for the underground development. The underground mine design is based on the use of conventional mechanised mining and underhand sublevel stoping.

In the Boston Shaker underground, mining comprises unfilled long-hole open stoping with support pillars. The planned underground ore production rate is ~1.4Mt/a with commercial production rates from Boston Shaker underground.

The Joint Venture has awarded the underground mining contract to Macmahon, a leading surface and underground mining services business.

The Tropicana, Havana, Havana South and Boston Shaker open pits have been mined as a series of cutbacks, sequenced and scheduled to maximize value at a mining rate that delivers the best mining unit cost for the scale of the operation. Up until June 2020 ore production from the open pits exceeded the plant capacity, allowing higher grade ore to be preferentially treated (grade streaming) while lower grade ore was accumulated on stockpiles.

Over the course of H2 2019 and H1 2020 the Tropicana pit and Havana pit were completed, in line with the mine plan. As a result, grade streaming came to an end and stockpiled ore is currently being used to supplement the mill feed from the Havana South and Boston Shaker pits.

A decision was made in the June 2020 quarter to invest in the next cutback of the Havana pit (Stage 2) which will allow access to the deeper Havana open pit ore from 2022 onwards. While this cutback is being completed, mill feed will be sourced from the Boston Shaker open pit, supplemented by approximately 4 Mtpa of low grade (0.85 – 1.05 g/t) stockpiled ore, resulting in a lower milled grade over the period.

The lower grade will be partially offset by the Boston Shaker underground mine, which is ramping up and will be contributing at full capacity by the second half of calendar 2021.

The plan remains for gold production (at 100%) in 2020 and 2021, to be between 400,000 and 450,000 oz, compared to 513,785 oz last year. From 2022 onwards, annual gold production will normalize at between 450,000 – 500,000 oz as the low grade stockpile ore in the mill feed is displaced by a larger proportion of Boston Shaker underground ore and an increasing contribution of higher grade ore from the Havana pit, as the cutback progresses.

For open pit mining at Tropicana, excavators and face shovels load trucks from 12m to 15m high benches, with a vertical advance rate of ~90 to 145m/a in the mine schedule – with >160m achieved in 2020 in the Boston Shaker pit.

- subscription is required.

The processing plant has a current capacity of 9.3Mtpa. The crushing circuit consists of a primary gyratory crusher, feeding a set of secondary cone crushers and tertiary rolls crushers. A 14MW and 6MW ball mill in parallel completes the grinding circuit. A CIL circuit is used to extract the gold from the ore, and a standard AARL elution and recovery systems is used to form gold bars.

The power provider, Kalgoorlie Power Systems, has built a dedicated power station consisting of a combination of diesel and gas powered generators with a capacity of 48.5MW.