Pb-Zn-Ag orebodies at Mount Isa are broadly stratiform with a 60-65° westerly dip parallel to bedding in the host Urquhart Shale. The main stacked group of orebodies defines and en-echelon group of north-plunging lenses which are bounded to the south by the silica-dolomite alteration zone associated with the copper orebodies and to the north by the NNW-plunging Mount Isa Fold (Davis 2004).

The stratiform zone of Zn-Pb-Ag and pyrite enrichment within the Urquhart Shale is much more laterally extensive than the economically-defined orebodies (Painter, 2003), extending along stratigraphically consistent zones for more than 10km north of the economic limit of mineralisation.

Mount Isa’s stratiform silver-leadzinc sulphide mineralization occurs with pyrite and pyrrhotite in distinct bands dipping to the west, concordant with weakly bedded carbonaceous dolomitic sediments of the Urquhart Shale. The mineralization is intermittent through a stratigraphic interval of over 1 km, but the major orebodies are restricted to the upper 650 m. The orebodies occur in an echelon pattern, interlocking at the southern and lower sections with the extremities of the silica-dolomite mass hosting the copper orebodies.

Brittle-ductile deformation predominates in the mine, with common development of disharmonic folding within the Pb-Zn orebodies. Pb-Zn mineralisation is stratiform, but abundant evidence exists of hand specimen-scale transitions from ore layers to barren ........

Mt Isa zinc assets involve the 4.5 million tonne per annum George Fisher underground mine and the 1.6 million tonne per annum Lady Loretta underground mine, which is operated by RedPath Australia. The Black Star open cut was moved to a care and maintenance phase during the last quarter of 2016 after mining out the existing reserves.

A feasibility project for George Fisher Mine was conducted from 2009 to 2014 installing a new materials handling system and opening up a new mining block down to 1,160 metres at the Northern end of the George Fisher orebody with the capacity to increase production to 4.5 million tonnes of ore per annum.

The current extraction method at George Fisher is sublevel open stoping.

Production began at the Lady Loretta in 2013 and the mine was placed on care and maintenance in 2015 before its restart in March 2018. With a nameplate annual ore capacity of 1.6 million tonnes, Lady Loretta can produce as many as 160,000 tonnes of zinc per year over its remaining six-year mine life.

The mining method utilized at Lady Loretta is conventional sub-level open stoping (a slot is opened up using a Redbore 30 raisebore raise drill) with paste used to fill the void upon completion.

The Handlebar Hill Open Cut mine was placed in care and maintenance in July 2014.

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