The Mungari Operation includes the Frog’s Leg and White Foil mines
600km east of Perth, 20km west of Kalgoorlie, Western Australia, Australia
Year commenced operations
Frog’s Leg: underground commenced August 2007 after being open pit mined in 2004 and 2005
White Foil: open pit recommenced mid 2014 following construction of the Mungari plant. It previously produced for brief periods at a time (2002-2003 and later in 2010-2011)
1996: Discovery of White Foil deposit (Mines and Resources Australia Pty Ltd, 51% (“MRA”) and Aurion Gold 49%)
2002-2003: White Foil open pit production (toll treatment)
2010-2011: Period of White Foil open pit mining (toll treatment)
Mid 2014: Full scale mining of White Foil recommenced
1999: Discovery of Frog’s Leg deposit (MRA)
2004: Frog’s Leg open pit production commenced June 2004 (toll treatment)
2005: Frog’s Leg open pit production ceased in October 2005
2007: Frog’s Leg underground mining commences August 2007
Style of mineralisation
Gold mineralisation at White Foil occurs in the quartz gabbro portion of a mafic sill that has intruded the volcaniclastic Black Flag sediments and is associated with quartz veining and stockwork veining. The mineralised zone is 70m wide, 400m long and dips to the WSW and WNS at between 50° to 60° and is open at depth.
The Frog’s Leg ore lodes occur at the steeply west dipping sheared contact between the Black Flag Volcaniclastics to the east and basalts to the west and gold is hosted in quartz veins and breccia. The ore lodes are between 2m and 20m thick and occur as sub-parallel lodes.
Measured, Indicated and Inferred Resources (at 31 Dec 2015)
23.58Mt at 2.33g/t gold for 1.8Moz
Ore Reserves (as at 31 Dec 2015)
7.92Mt @ 2.61g/t gold for 665koz
Frog’s Leg – underground operation
White Foil – open pit operation
3 stage crushing-grinding-CIL
1.5Mtpa nameplate capacity (currently operating at 1.6Mtpa)
The White Foil and Frog’s Leg deposits are situated within the Norseman-Wiluna Greenstone Belt of the Yilgarn Craton, Western Australia. White Foil lies 3 km to the west of the Mungari Shear, a regional scale shear zone, and is hosted within a quartz rich gabbro unit which is part of the Powder Sill intrusive complex.
The Frog’s Leg deposit is located on the sheared contact between the porphyritic “cat rock” (regionally known as the Victorious Basalt) and volcaniclastic rocks of Black Flag Beds.
FY14 mine production of 125,000 ounces of gold was delivered from the Frog’s Leg underground operation. White Foil open-pit operation re-commenced mid 2014 and is expected to deliver annual production in excess of 40,000 ounces of gold.
Underground methodology employed at Frog’s Leg is top-down bench stoping with paste fill.
White Foil is an open pit mine utilising conventional drill and blast, load and haul methods.
The onsite 1.5Mtpa Mungari processing plant was completed on-time and on-budget (A$110 million) in June 2014. The processing plant consists of 3 stage crushing and ball milling, followed by conventional leaching.
White Foil now benefits from lower processing and haulage costs, making a larger portion of the resource economic. Driven by this ability to process the White Foil ore, exploration resumed in late 2012 and resulted in a 4-fold increase to reach an endowment of nearly 2 Moz.