All known mineralisation in the area is epigenetic “Cobar” style. Deposits are structurally controlled quartz + sulphide matrix breccias grading to massive sulphide.

The deposits are located in high strain zones. Metal ratios are variable but there is a general tendency for separate Pb+Zn+Ag±Au±Cu and Cu+Ag±Au ore bodies. These are often in close association with the Pb+Zn lenses lying to the west of the Cu lenses. At Hera Zn is usually more abundant than Pb.

Formation temperatures are moderate to high. At Hera the presence of Fe-rich sphalerite, nonmagnetic pyrrhotite and cubanite indicates formation temperatures between 350°C and 400°C. Recognised at Hera are quartz + K-feldspar veins, scheelite, and minor skarn mineralogy which suggest a possible magmatic input. Deposit timing is enigmatic. The main mineralisation occurs as brittle sulphide matrix breccias with silicification grading to ductile massive sulphides that crosscut both bedding and cleavage. Recent age dating on micas and galena gives an age of ~385Ma for the Hera deposit.

The mineralisation at Hera, indicated by elevated gold, silver, lead, zinc and sulphur grades, appears to be structurally controlled and is associated with shearing, brecciation and quartz veining.

The twelve solid wireframes representing mineralised domains were treated as hard boundaries during estimation of all elements except arsenic. This means that blocks inside a particular domain were estima ........

Hera is an underground mine utilising bench stoping with the stopes backfilled with waste rock fill.

The Hera orebody is accessed from a decline located in the hanging wall. The decline has a gradient of 1:7 and production levels are nominally 25m apart.

Mining is undertaken using conventional bench stoping mining techniques. Stope voids are backfilled with waste rock material from concurrent underground development and, if required, additional waste rock material is transported from the WRE Area on the surface.

Sill pillars are every 100m vertically with an open stoping method adopting a yielding pillar above and between the previously filled panels. Level access is via the hangingwall (east) decline and the decline has a standoff of 50m from the ore body. The decline face is currently 620m vertically below surface and the sublevels are spaced vertically at 25m. Stopes are typically 30m long, 25m high and 8m wide. Stopes are demonstrating stable characteristics up to a hydraulic radius of 7.5m or approximately 30m along strike.

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