PGM mineralisation at Mimosa is located in four erosionally isolated and fault-bounded blocks, namely, from north to south, the North Hill orebody, South Hill orebody, Mtshingwe Fault Block orebody and Far South Hill orebody areas. Each of these blocks is host to a pyroxenite layer known as the P1 pyroxenite layer which is overlain by a layer of gabbro. The platinum-bearing Main Sulphide Zone (MSZ) is located in the P1 pyroxenite some 10m below the ultramafic/mafic contact. The MSZ is a continuous layer, 2m to 6m thick, and forms an elongated basin. The zone strikes in a north-northeasterly trend and dips at about 14° on the margins flattening towards the axis of the basin. The MSZ at Mimosa has a well-defined grade profile where peak base metal and PGM values are offset vertically, with palladium dominant towards the base, platinum in the center and nickel towards the top. At Mimosa the MSZ is visually identified using pyroxene and sulphide mineralisation followed by confirmatory channel sampling and underground XRF channel definition. Minor faults and dykes are present at Mimosa. Although no potholes have been identified, low-grade areas and areas of no mineralisation, or ‘washouts’, have been intersected. These are all accounted for in the Mineral Resource and Mineral Reserve estimate.

Mimosa is a shallow underground mine accessed by the two decline shafts, Wedza Decline and Blore Shaft. Mechanised bord and pillar mining method is used to extract ore over average stoping width of 2.1m. Historically, the bord widths have varied from 15m to 6m wide, depending on the ground control district. Minimum pillar sizes are dependent on depth to give a safety factor greater than 1.6. Current mining consists of 5.5m to 7m bord sizes with 8m by 4m pillars for the entire mine.

The mining cycle involves mechanised support drilling and installation, MSZ channel definition and marking, mechanised face drilling, charging and blasting, followed by mechanised lashing onto a conveyor network feeding to an underground bunker. The ore is conveyed to a surface stockpile ahead of feeding into the processing plant from the bunker. Optimum stoping widths and mining cut selection are regularly reviewed. The currently planned mining horizon is a 2.1m slice defined by the hangingwall at 0.60m above and the footwall at 1.5m below the Platinum peak. This overbreaks to an actual mining width average of 2.14m.

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