The stratigraphy covered by the KCGM tenements consists of a basal ultramafic unit called the Hannan Lake Serpentinite. This ultramafic unit is overlain successively by the high magnesian Devon Consols Basalt, Kapai Slate, tholeiitic Paringa Basalt and the Black Flag sediments. Differentiated zones of dolerite and gabbro texture occur within the mafic sequence. The Golden Mile Dolerite, hosting the bulk of the Golden Mile and Mount Charlotte gold mineralisation, is a strongly differentiated layered gabbro, approximately 700m in thickness. The Golden Mile Dolerite is situated conformably between the Paringa Basalt and the Black Flag sediments. This entire stratigraphic sequence is intruded by numerous porphyry dykes of intermediate to felsic composition.

The Mt Charlotte style gold mineralisation is hosted within the Golden Mile Dolerite and is predominantly associated with pyrite in carbonate alteration haloes around quartz veins, with a minor proportion as relatively coarse free gold within the veins, commonly close to their margins. The veins vary in width from a few millimetres to a maximum of about two metres but are commonly between two centimetres and 50 cm wide. The vein spacing varies from 20 cm to tens of metres but is typically from 50 cm to two metres in areas mined as ore. Quartz is the dominant vein-fill mineral; accessory vein minerals include calcite, ankerite, scheelite, pyrite, pyrrhotite, and gold.

The Hidden Secret style gold mineralisation is hosted within the Williamstown Dolerite at the contact with the Kapai Slate and Devon Consols Basalt and spatially associated with a porphyritic intrusion and the Towns Fault. Gold is hosted in deformed a quartz vein 2- 20cm wide. Vein minerals include pyrite, telluride, silica, carbonate and fuchsite.

Multiple drill programs were completed in FY2020 across various project areas at Mt Charlotte. Results are encouraging with more drilling planned in FY2021 as the full scale of the mineralised system and how it interacts with Fimiston is being modelled and tested. [2020, AR, p.20]

Mt Ferrum is a shear-hosted Fimiston-style lode located 600m east of the Sam Pearce decline of the Mt Charlotte mine. Mineralisation is hosted within Paringa Basalt and strikes NNE. Infill resource definition drilling has identified a series of hangingwall and footwall structures, and stockwork mineralisation in Williamstown Dolerite to the west of the main lode. Mineralisation is thought to be controlled by the structural architecture and is the subject of a geological review currently underway. [2020, AR, p.20]

Kal East is a narrow, high-grade Fimiston-style lode lying 250m to the east of existing infrastructure at the Mt Charlotte mine. Infill resource definition drilling has identified more complexity than expected, defining a series of hangingwall and footwall structures. Mineralisation is hosted primarily within Williamstown Dolerite and the highest grade is constrained within a steeply dipping southerly plunging shoot. Internal zones within the Williamstown Dolerite are important in controlling the distribution of gold. [2020, AR, p.20]

Belgravia is a series of mineralised lodes lying 100m north of existing infrastructure at the Mt Charlotte mine. Mineralisation is hosted within pillowed and variolitic Devon Consols Basalt in proximity to the Hannans Lake Serpentinite, the contact of which is intruded by felsic porphyritic rocks. Infill resource definition drilling has identified eight separate NNW- striking lodes with en échelon geometry. The lodes are overprinted by stockwork mineralisation, with veins dipping to the north similar to the Mt Charlotte-style stockwork orientations. [2020, AR, p.20]

Mt Charlotte Mining Infrastructure includes:
- Glory Hole Pit;
- Underground Mine; and
- Surface Operations (including headframe, conveyor and core yard).

Glory Hole Pit
The Mt Charlotte Glory Hole is immediately to the north of the Cassidy Headframe, located at the eastern end of Hannan Street. When the Mt Charlotte E1 crown pillar was removed in 1978 the Glory Hole was joined with the underlying stopes of the Mt Charlotte Underground Mine. Crushed rock from the Fimiston Open Pit is transported to the Glory Hole via conveyor, where it is utilised for backfilling the underground stopes at Mt Charlotte and buttressing of the Glory Hole Pit.

Mt Charlotte Underground Mine
Mining at Mt Charlotte commenced in 1893, however, large-scale mining did not commence until 1962. Operations at Mt Charlotte initially centred on the Reward Shaft and the Man & Supply Shaft (decommissioned). The Cassidy Shaft and associated headframe were developed in the early 1980s to access deep ore, with the Cassidy headframe still currently in place. Mt Charlotte is currently the only active underground operation managed by KCGM and is scheduled to continue production until 2024.

The main historical method of mining at Mt Charlotte was open stoping. Typically, large stable open stopes were mined and then the rib/crown pillars were mass blasted, with waste rock fill above cascading onto the broken ore. Currently stoping under rock fill (SURF) is used to recover remnant resources. Extraction is from drawpoints until waste rock dilution becomes excessive. Ore from Mt Charlotte is transported to the Fimiston Plant via the Sam Pearce Decline. The underground stopes are backfilled with either mine waste or crushed rock for stability purposes. Fill is delivered through the Glory Hole. Development of the Hidden Secret deposit located 400m east of Mt Charlotte commenced during 2016. Planned stope extraction will utilise the modified Avoca method.

Surface Operations
Cassidy Headframe and Vent Shafts
The Cassidy Headframe and shaft at Mt Charlotte are maintained as a primary form of egress, while the Sam Pearce Decline acts as the primary access; several other smaller vent rises assist with underground ventilation. The Cassidy Headframe is the last headframe remaining on the Golden Mile and has been identified by the community for potential retention for heritage and tourism purposes. The associated winders and winder house may also be retained.

Core Yard
This feature covers the geology core yard at Mt Charlotte. The core yard is currently utilised by KCGM and will remain in use while KCGM has an active drilling programme. As part of general activities, the drill core is periodically reviewed and disposed of when no longer required.

Overland Conveyor
A conveyor previously used to transport ore has been reversed and is now used to convey waste rock from the Fimiston Operational Area to the Glory Hole for underground fill. The conveyor passes under Boorara Road and over Williamstown Road. An unsealed access road is in place along the length of the conveyor.

The Mt Charlotte Underground Mine currently produces ore at the rate of 1.15M tonnes per annum (tpa) which is transported directly to the ROM at the Fimiston Plant via the Sam Pearce decline located within the Fimiston Open Pit north eastern wall. Waste rock produced during mining at Mt Charlotte is not brought to the surface, instead it is used to backfill underground voids. Small volumes of waste rock from the Fimiston Open Pit are crushed at Fimiston before being conveyed to the ‘Glory Hole’ Pit to be used for backfilling of underground stopes at Mt Charlotte.

The Mt Charlotte Underground Mine is situated in Golden Mile Dolerite that is offset by two major faults; the Flanagan and Charlotte Faults. Currently the mine has relatively small natural groundwater inflows, but historically has had significant inflows associated with groundwater issuing from fractures in the proximity to the Charlotte/Flanagan Fault. The Mt Charlotte Operations are not hydraulically connected to the Fimiston Open Pit due to the presence of a fault that acts as a barrier between these areas. Dewatering of Mt Charlotte currently occurs ahead of mining.

The Fimiston Processing Plant comprises two parallel circuits for processing refractory sulphide ore from the Fimiston Open Pit and ore from the Mt Charlotte Underground Mine.

The processes undertaken in the Fimiston Processing Plant are outlined below:
- Two crushing circuits that supply coarse ore as a mill feed stockpile;
- Two milling circuits, the Fimiston and the Mt Charlotte. The Fimiston circuit comprises a semiautogenous grinding (SAG) mill and a pebble crushing circuit with two secondary ball mills and four Knelson concentrators. The Mt Charlotte circuit is a single SAG mill and ball mill with a single Knelson concentrator;
- A flotation circuit and three carbon-in-leach (CIL) circuits through which milled ore is processed;
- Filtration and Ultra Fine Grind (UFG) via a carbon in leach circuit through which flotation concentrates are de-slimed and processed;
- A gold recovery circuit comprising an Acacia reactor, elution, electrowinning, sm ........