The Outpost Island Mine was a gold and tungsten producer 94 kilometres southeast of Yellowknife, Northwest Territories on an island of Great Slave Lake.
 Gold was discovered here in 1935 by prospectors, and some development was undertaken in 1936-1938.
 Tungsten ores became valuable during World War II, so the owners (Slave Lake Gold Mines Limited) investigated the tungsten possibilities of the mine.
 It produced small amounts of gold, copper, and tungsten during 1941-1942, and then again in 1951-1952 during the Korean War.
 It was a small deposit and was not considered economic because of unpredictable tungsten market prices in the 1950s.
Mina Invierno (lit.
 "Winter Mine") is a coal mine in Riesco Island, Chile, that as of August 12 of 2012 is under construction.
 The mine is expected to export coal to northern Chile and to other countries.
 The enterprise in charge of the project has declared the works will occupy an area of 1500 ha representing 0.3% of the area of Riesco Island.
The Batu Hijau mine is an open pit copper-gold mine operated by Newmont Mining Corporation's subsidiary company PT Newmont Nusa Tenggara (PT Newmont).
 The mine is located 1530 km east of the Indonesian capital Jakarta on Sumbawa, in southern Taliwang Regency, an island in West Nusa Tenggara.
 The mine is the result of a ten-year exploration and construction program based on a 1999 discovery of the porphyry copper deposit.
 Production began in 2000.
The Simberi mine is one of the largest gold mines in Papua New Guinea and in the world.
 The mine is located in the north of the country on Simberi Island, New Ireland Province.
 The mine, owned by St Barbara Limited, has estimated reserves of 3.3 million oz of gold.
Copperfields Mine, originally known as Temagami Mine, is an abandoned copper and silver mine on Temagami Island in Lake Temagami, Ontario, Canada.
 The mine opened in 1955 and comprises both underground and surface workings within a sulfide ore body.
 Situated in Phyllis Township, the mine produced 34,000,000 dollars Canadian with 80 million pounds of copper, 230,028 ounces of silver and 13,271 ounces of gold.
 It was considered to be the largest deposit of nearly pure chalcopyrite ever discovered in Canada.
 A mill was not initially needed because the ore was 28% copper.
 The mine closed in 1972 and is now flooded by water.
 Ruins of the Copperfields mill are present as foundations.
 It is possible to find mineral specimens in the spoil heaps of the old mine, such as chalcopyrite, pyrite, bornite, malachite, dolomite, hessite, merenskyite, millerite, palladium, quartz and others.
 The Lake Temagami Access Road was created to ship ore from the mine site.
Polaris zinc mine was an underground zinc mine on Little Cornwallis Island in the Canadian territory of Nunavut (Northwest Territories prior to Nunavut's official separation).
 The Polaris mine was located 1120 km north of the Arctic Circle, and 96 km north of the community of Resolute.
 The Polaris mine closed in July 2002 following more than twenty years of zinc production.
The Pike River Mine disaster was a coal mining accident that began on 19 November 2010 in the Pike River Mine, 46 km northeast of Greymouth, in the West Coast region of New Zealand's South Island.
 A methane explosion occurred in the mine at approximately 3:44 pm (NZDT, UTC+13).
 At the time of the explosion 31 miners and contractors were present in the mine.
 Two miners managed to walk from the mine; they were treated for moderate injuries and released from Greymouth Hospital the next day.
 The remaining 16 miners and 13 contractors, often referred to as "the twenty-nine", were believed to be at least 1500 m from the mine's entrance.
Temagami Island, formerly spelt as Timagami Island, is an island in Lake Temagami in Northeastern Ontario, Canada.
 It is the largest island within the lake, with Bear Island coming second.
 The island has many hiking trails that lead into the old-growth forest that is a mix of large white and red pine trees.
 Temagami Mine, later known as Copperfields Mine, was a copper mine that opened on Temagami Island in 1954.
 It was considered to be the largest deposit of nearly pure chalcopyrite ever discovered in Canada.
 The mine closed in 1972.
The Salmita Mine was a gold producer in the Northwest Territories, Canada during 1983 to 1987.
 The deposit was first discovered in 1945 and underground exploration was carried out in 1951-1952.
 It was reactivated for exploration by Giant Yellowknife Mines Limited in 1975 and entered production in 1983.
 They used the old camp and milling plant of the abandoned Tundra Mine, located a few kilometres to the south.
 The mine produced 179,906 troy ounces (5596 kg) of gold from the milling of 238,177 tons of ore.
The Gag Island mine is a large mine in the east of Indonesia in Sulawesi.
 Gag Island represents one of the largest nickel reserve in Indonesia having estimated reserves of 240 million tonnes of ore grading 1.35% nickel.
 The 240 million tonnes of ore contains 3.24 million tonnes of nickel metal.

Question: What did Salmita Mine and Outpost Island Mine both mine for 
Answer: Gold