Tomingley Deposits
Mineralisation is associated with quartz veining and alteration focused within sub volcanic basaltic-andesite sills and adjacent volcaniclastic sediments. The deposits appear to have formed as the result of a rheological contrast between the porphyritic sub-volcanic sills and the surrounding volcaniclastic sediments, with the sills showing brittle fracture and the sediments ductile deformation, and have many similarities to well documented orogenic-lode style gold deposits.

Mineralisation at Wyoming One is developed within a number of different zones:

- porphyry – mineralisation hosted by a quartz stockwork within the carapace of a subvolcanic sill with dimensions roughly 60m x 150m. High grade mineralisation is developed along the eastern contact of the zone (‘contact’ zone);

- hangingwall – a linear zone of mineralisation situated approximately 30m to hangingwall of the ‘porphyry’ mineralisation and hosted within silicified and brecciated carbonaceous mudstone. This zone is interpreted to fold around the northern end of the porphyry (northern zone);

- ‘376’ – east west zone of high grade mineralisation developed at the northern contact of the porphyry. Interpreted to be a bounding structure and primary fluid conduit. Other high grade east-west structures e.g. ‘831’ appear to be developed en-echelon and to the south of the ‘376’ zone;

- footwall – a low grade zone located in a similar stratigraphic position to the hangingwall zone but footwall to the porphyry.

The mineralisation occurs in several zones within a NNW-striking corridor 300m long and 220m wide. Mineralisation extends from about 25m below the surface for more than 400m vertical depth.


Caloma One
Mineralisation at Caloma is developed within a series of stacked ‘quartz lodes’ which dip shallowly to the west and hosted dominantly within the sub-volcanic sills. The lodes are cross cut by a number of barren post mineralisation dolerite dykes.

The mineralisation occurs in several west-dipping zones within a north-striking corridor 460m long and 420m wide. Mineralisation extends from about 5m below the surface for more than 350m vertical depth.

Caloma Two
Mineralisation at Caloma Two is developed within a series of ‘quartz lodes’ which dip north at flat to moderate angles and hosted dominantly within the sub-volcanic sills. Mineralisation is also developed along a sediment contact zone which appears to be a potential linking structure with the Caloma mineralisation to the north. There is also evidence for the development of an inverted saddle reef at depth. The lodes are cross cut by a number of post mineralisation dolerite dykes.

Current mining activities comprise of underground mining of Wyoming One and access development to the Caloma orebodies.

Two mining methods are used to mine the underground resource including Longhole Open Stoping (LHOS) with cemented rockfill or rockfill, and LHOS with rib pillars and no fill. The choice of mining method is determined by value of the resource, orebody width and geotechnical factors.

Stoping configurations are predominantly single-lift stoping (25m vertical interval) with strike length of 20-25m. The stoping method involves establishing a slot using conventional long-hole drill and blast techniques and then the stoping front is retreated along strike. The installation of brow cables and the use of a concurrent strike-retreat blasting sequence assist in controlling ground stability. Depending on the mining method used cemented rockfill or loose rockfill is filled into the stopes upon completion of mining. For the LHOS with rib pillars there is no placement of fill.

Ore production is scheduled at 840 ktpa which is trucked to surface using a fleet of four underground trucks. The truck fleet is matched with four Caterpillar R2900 loaders operating on a combination of teleremote and manual control. Normal drilling fleet includes two development jumbos and two production drills.

The plant consists of a crushing circuit, single-stage milling circuit and hybrid carbon-in-leach (CIL) circuit with one designated leach tank and numerous adsorption tanks. Gold is recovered from activated carbon into concentrated solution. Electrowinning and smelting are conducted in an adjacent secure gold room. The tailings from the process are thickened and pumped to a paddock type tailings storage facility with multi-spigot distribution

The plant has a designated throughput of 1.25mtpa of oxide ore and 1.0mtpa of fresh (sulphide) ore. The plant has been operational since February 2014.