Name of the Mine
Simberi Operations.

Location  
The Simberi Operations are located on Simberi Island, in the Tabar Islands Group situated in the New Ireland province of Papua New Guinea.

Mine Owner/s  
St Barbara.

Brief Description  
The Simberi Operations’ known gold prospects include Sorowar, Pigiput, Pigibo, Botlu, Pigicow, Samat, Bekou and Monun Creek.

Of the eight deposits, Pigiput in the south is by far the biggest gold resource. Monun Creek is located immediately to the north-east of Pigiput, with Sorowar, the second-biggest resource, further north again. Pigibo, Botlu, Samat and Bekou are situated to the west and south of Pigiput, and while relatively small, are relatively higher grade.

Fine grained free gold in oxide material is the target of current operations.

Brief History  
Operations started at Simberi in 2008.

Primary Metals/Minerals  
Gold.

Secondary Metals/Minerals  
None stated.

Geology/Mineralisation  
Simberi is the oldest and northernmost island of the Tabar Group. It is about 10 km east to west, 8 km north to south and rises to more than 300 m above sea level.

The currently known gold prospects on Simberi Island – Sorowar, Pigiput, Pigibo, Botlu, Pigicow, Samat, Bekou and Monun Creek – are situated within 2 km to 3 km of each other, in the eastern half of the island within the central volcanic core. They are contained within a subcropping epithermal alteration system and structural corridor extending 4 km north to south and 2 km east to west.

The host rocks for the mineralisation comprise Pliocene altered alkaline lava flows or intrusives (porphyries), volcaniclastics and tuffs.

Within the sulphide zone, gold is also fine grained (most grains are under 15 μm in diameter) but is generally within pyrite.

St Barbara notes in its ‘Ore Reserves and Mineral Resources Statements as at 30 June 2021’ report that modifications are required to the current processing plant to enable the flotation of pyrite and recovery of the gold.

The grade of the mineralisation pertains to the natural porosity and degree of fracturing of the host rocks, greatest in the vicinity of steep and moderately dipping feeder structures interpreted to have been the pathways for alteration and mineralising fluids.

Reserves
Total proven and probable reserves as at June 30, 2021, were estimated at 35.25-million tonnes grading 1.8 g/t gold.

Resources  
Total mineral resources as at June 30, 2021, were estimated at 90.11-million tonnes grading 1.4 g/t gold.

Mining Method  
The mining method for all deposits is openpit.

Major Infrastructure/Equipment  
Simberi includes an oxide processing plant, process plant buildings, administration offices, training rooms, an assay laboratory, site security buildings, ablution facilities and stores.

Prospects  
An upcoming sulphide project has the potential to extend the life-of-mine by at least ten years.

Contact Details
St Barbara
Tel +61 3 8660 1914
Website https://stbarbara.com.au

Sources
St Barbara. Ore reserves mineral resources statement as at June 30, 2020 (August 24, 2020).
St Barbara. Website https://stbarbara.com.au (accessed January 24, 2022).