MGO is located in the Achaean Murchison Province, a granite-greenstone terrane in the northwest of the Yilgarn Craton. Greenstone belts trending north-northeast are separated by granite-gneiss domes, with smaller granite plutons also present within or on the margins of the belts.

The Paddy’s Flat area is located on the western limb of a regional fold, the Polelle Syncline, within a sequence of mafic to ultramafic volcanics with minor interflow sediments and banded iron-formation. The sequence has also been intruded by felsic porphyry dykes prior to mineralisation. Mineralisation is located along four sub-parallel trends at Paddy’s Flat which can be summarized as containing three dominant mineralisation styles:
• Sulphide replacement BIF hosted gold. Quartz vein hosted shear-related gold.
• Quartz-carbonate-sulphide stockwork vein and alteration related gold.

The Yaloginda area is a gold-bearing Archaean greenstone belt situated ~15km south of Meekatharra. The deposits in the area are hosted in a strained and metamorphosed volcanic sequence that consists primarily of ultramafic and high-magnesium basalt with minor komatiite, peridotite, gabbro, tholeiitic basalt and interflow sediments. The sequence was intruded by a variety of felsic porphyry and intermediate sills and dykes.

The Reedy’s mining district is located approximately 15 km to the south-east to Meekatharra and to the south of Lake Annean. The Reedy gold deposits occur with- in a north-south trending greenstone belt, two to five kilometres wide, composed of volcano-sedimentary sequences and separated multiphase syn- and post-tectonic granitoid complexes.

The Paddy’s Flat Trend is mineralised a strike length of >3,900m, a lateral extent of up +230m and a depth of over 500m.

Bluebird is mineralised a strike length of >1,800m, a lateral extent of up +50m and a depth of over 500m.

Triton – South Emu is mineralised a strike length of >1,100m, a lateral extent of several meters and a depth of over 500m.

The Bluebird plant receives underground ore from the Paddy’s Flat, South Emu - Triton and Bluebird underground mines and supplementary lower grade open pit ore from Five Mile Well, Maid Marion, Albury Heath and Aladdin open pits.

The Bluebird underground mine recommenced in FY21, following the temporary suspension of development works due to a skilled labour shortage. During the temporary closure, an extensive underground drilling program was completed producing excellent results and extending the resource significantly.

With the recommencement of mining at Bluebird, Westgold now operates three underground mines at MGO, including Paddy’s Flat and South Emu – Triton. At steady state production, these three mines are expected to deliver more than 100,000oz per annum to the Bluebird processing plant with potential supplemental ore available from the Aladdin, Albury Heath and Maid Marion deposits.

Open Pit
A majority of the open pits have a final design wall angle of 39-46 degrees. Dilution of the ore through the mining process has been accounted for within the Ore Reserve quoted inventory. Various dilution ratios are used to represent the style of mineralisation. Minimum mining widths have been accounted for in the designs, with the utilisation of 40t or 90t trucking parameters depending upon the size of the pit excavation.

Underground
In large disseminated orebodies sub level caving, sub level open stoping or single level bench stoping production methodologies are used. In narrow vein laminated quartz hosted domains a conservative narrow bench style mining method is used. In narrow flat dipping deposits a Flat Long Hole process is adopted (with fillets in the footwall for rill angle) and or jumbo stoping. Minimum mining widths have been applied in the various mining methods.

The MGO (Meekatharra Gold Operations) project hub incorporates the 1.6-1.8 Mtpa Bluebird processing hub.

MGO has an existing conventional CIL processing plant – which has been operational in various periods since the late 1980’s.

Gold extraction is achieved using single stage crushing, SAG & ball milling with gravity concentration and Carbon in Leach.

A long history of processing through the existing facility demonstrates the appropriateness of the process to the styles of mineralisation considered.

No deleterious elements are considered, as a long history of processing has shown this to be not a material concern.