SASA Mine comprises the Svinja Reka, Golema Reka and Kozja Reka lead-zinc-silver deposits, which lie within the Serbo-Macedonian Massif, a belt which extends through Serbia, Macedonia, Bulgaria, and eastern Greece into Turkey and hosts a large number of lead-zinc deposits. The mineral deposits are located on the eastern flank of a Tertiary intermediate intrusive complex and related porphyry Cu-Mo system, within which a northwest striking stockwork alteration zone is developed. Lead-zinc-silver mineralisation occurs as stratiform deposits hosted predominantly by quartz-graphite schist and marbles of Lower Palaeozoic age at Svinja Reka and by gneisses at Golema Reka. The mineralisation is considered to relate to the intrusion of Tertiary volcanics. High-temperature hydrothermal fluids and bedding-parallel faulting are responsible for metasomatism of the host sediments, producing skarn and base metal mineralisation.

The well-defined, partially exploited, lenses of lead-zinc-silver mineralisation dip at approximately 35° to the south-west and typically range in true thickness from between 2 and 30 m. The mineralised lenses are present in parallel sheets (typically two or three bodies, namely the hanging wall, central and footwall orebodies), separated by an interburden with thicknesses of 1 to 10 m. The lenses pinch and swell along strike and down-dip. The mineral deposits are considered to be metasomatic skarn-hydrothermal deposits with replacement and bedding-paralle ........

Sasa is an underground zinc and lead mine that produces approximately 820,000 tonnes of ore each year. Accessed by adit, the Svinja Reka deposit is currently mined using a sub-level caving method, which utilises the geotechnical characteristics of the weak hanging wall to allow the rock to cave naturally into the void remaining after ore has been blasted.

Main haulage levels are at 80 metre intervals, with sub-levels every 7 metres. Ore drives are typically 3.5 metres by 3.5 metres. Ore is mined using a top down approach without backfill. Ore is drilled using single boom jumbos, blasted and then excavated with underground loaders.

From the second half of 2022 the Sasa team will transition to a new mining method, cut and fill stoping, with approximately 90% of ore being extracted using this method by 2024. The voids will then be backfilled with paste material containing tailings to provide support, rather than allowing the roof to cave as is the case with the current sub-level caving method.

Once blasted, 70% of the ore is then sent via ore passes to the 830m level where it is transported by rail wagons to the Golema Reka shaft for hoisting, and the remaining 30% is hauled to surface via the adit.

A total of 806,069 tonnes of ore were mined using the sub-level caving method during the 2022 year from the 990 metre and 910 metre working areas. The ore from the underground operations is hoisted via the Golema Reka shaft to surface (c.73 ........

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