Simberi Island

2°37′29.33″S 151°58′25.96″E / 2.6248139°S 151.9738778°E / -2.6248139; 151.9738778ArchipelagoBismarck ArchipelagoArea40 km² (15 sq mi)Highest elevation340 m (1120 ft)AdministrationProvinceNew Ireland ProvinceDemographicsPopulation1100^[1]

Simberi Island is a volcanic island in the Tabar Group, in Papua New Guinea's New Ireland Province.^[1]

Simberi is the northernmost and smallest of the three islands in the Tabar Group. The island is about 9 km (5.6 mi) long and 7 km (4.3 mi) wide and has an area of about 40 square kilometers (15 sq mi). Its highest point in the highlands on the eastern side of the island is a 340 m (1,120 ft) eroded volcanic cone. The interior of the island is largely covered by rainforest. Most of the island's coast is steep and surrounded by a fringing reef together with a series of small islets. There is a woman shaped figure made by trees on the island and a barrier reef about 10 km (6 mi) offshore from the west coast. A 2 km (1 mi) strait separates Simberi from Tatau Island to the south west.

Simberi island is a potassium rich (high-K) calc-alkaline island arc volcano, the oldest in the Pliocene to Holocene Tabar-Lihir-Tanga-Feni (TLTF) volcanic arc that formed above a subduction zone.^[2][3]

The population is about 1100 and made up of nine clans who live in small coastal villages mainly in the north and west.^[1] The local language is a Simberi dialect of Mandara (also known as Tabar), ISO 639-3 language code "tbf", an Austronesian language spoken on the Tabar Islands.^[4][5]

The island has an airport, Simberi Airport (IATA airport code "NIS"), on the south east coast.^[6]

St Barbara Limited, an Australian-based company, operate an open pit gold (and silver) mine called the Simberi Oxide Gold Project in the volcanic highlands on the eastern side of the island.^[1] The mine is wholly owned and operated by St Barbara Limited, who acquired the assets of Allied Gold, the previous operators of the Simberi mine, on 31 August 2012.^[1] Gold production started in February 2008.^[1] Mining was suspended in December 2009 after Allied Gold received a cease work order from the Mineral Resources Authority of Papua New Guinea because of local landholder issues.^[1] Mining has since recommenced.^[1]

Seven gold deposits have been defined in mining lease 136 (ML 136), which covers the central and eastern portion of Simberi Island, and other prospects have been identified.^[1][6] The gold deposits occur mainly on ridge tops and are all within 2–3 km (1–2 mi) of each other.^[1][6] Sorowar in the north is the largest resource while Samat North, South and East to the south are relatively small but relatively high grade.^[6] Pigiput, Pigibo and Botlu South lie between the Sorowar and Samat areas and are of intermediate tonnage but at a grade similar to Sorowar.^[6] The western area of Simberi Island within exploration license EL 609 is largely unexplored.^[7] Reconnaissance exploration for both oxide and sulphide mineralisation is planned.^[7]

As of June 2009, Allied reported that the total resources were 4.7 million troy ounces (5.2 million ounces; 150 million grams) (Moz) gold, being oxide gold resources of 1.4 million ozt (1.5 million oz; 44 million g) and sulphide gold resources of 4.7 million ozt (5.2 million oz; 150 million g) together with 10.2 million ozt (11.2 million oz; 320 million g) silver.^[6]

Ore is delivered to the processing facilities on the eastern coast near Pigiput Bay by a 2,665 m-long (8,743 ft) RopeCon aerial conveyor that can deliver 600 tonnes (590 long tons; 660 short tons) of ore per hour.^[1][8] The process plant is a conventional carbon-in-leach (CIL) gold process plant capable of treating 2.2 million tonnes (2.2 million long tons; 2.4 million short tons) of ore per year.^[6] In September 2010, Allied announced that it planned to increase its gold production to 100,000 troy ounces (110,000 oz; 3,100,000 g) per year.^[7] The oxide processing circuit at the Simberi operation will be expanded to 3.5 million tonnes (3.4 million long tons; 3.9 million short tons) a year, by June 2013.^[9]

Mine tailings are disposed of in the form of a slurry that has been pre-diluted with seawater using a deep sea tailings pipeline.^[1] The pipeline is 528 m (1,732 ft) long with the discharge point at a depth of 130 m (430 ft). The tailings flow down a steep submarine slope and are deposited at a depth of more than 3 kilometers (1.9 mi).^[6]

Production for the period from 1 July 2009 to 30 June 2010 was 64,327 troy ounces (70,576 oz; 2,000,800 g).^[10]

In June 2009, Allied reported that the remaining mine life was estimated to be over 10 years.^[6] St Barbara Limited (Australia) acquired Allied in September 2012 and is the current owner of this mining operation.^[11] They are the largest employer on the island.^[6]