The Broken Hill deposit lies within the Broken Hill Group of the Palaeoproterozoic Willyama Supergroup and consists of nine separate but closely related orebodies that are stacked within a single stratigraphic package in the Hores Gneiss of the Broken Hill Group.

The impression that the Broken Hill orebodies are all massive sulphides with little else has long been dispelled.

Not only can different styles of mineralisation be identified but the information also gives valuable insights into the ways the deposit has responded to deformation and also to the predeformation characteristics of the deposit and therefore its genesis.

Massive sulphides form only a minor part of each orebody and are most common in deformed regions of the lenses. Sulphide-rich mineralisation is more often coarsely banded by variations in gangue mineral and sulphide abundance. Each orebody contains a high percentage of gangue minerals, including primary calcite, calcium or manganese pyroxenoids or pyroxenes, or quartz, that are distributed through the mineralisation as discrete bands, layers and stratigraphic horizons. Sphalerite (marrnatite) is the dominant sulphide constituent of all ore lenses and the percentage of galena diminishes in each orebody from 3L to BL.

Activities that are undertaken at the South Mine include the following:
- extraction of ore using underground mining methods. Ore and waste rock are removed from the mine using both shaft haulage and via decline. The mining is expected to be completed in 2030;
- crushing and screening of ore and stockpiling on a crushed ore stockpile;

The Rasp Mine is operated by CBH Resources Ltd. Operation of underground mine to extract ore at a maximum rate of 750,000 tpa, with mining expected to continue until 31 December 2026.

Mining ore from the Potosi mine is expected to be completed in 2021.

Mining activities at the North Mine:
- underground diamond drilling rigs targeting the upper section of mine area for exploration and blasting activities;
- transportation of ore and mullock to the surface using portal and decline via underground haul trucks;
- mullock placement occurred within existing Cosmopolitan open cut;
- extracted ore transported on sealed haulage route to surface ROM pad enclosure, a sealed, negative pressure building equipped with dust collection system.

Mining is principally conducted using a longhole open stope method with variations developed for extraction of the secondary resource located in the previously worked pillars area.

Longhole stoping currently accounts for 70 per cent of underground production, with pillar extraction and development ore contributing approximately 30 per ce ........

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