Oil and gas accounts for a major part of the nation’s foreign exchange earnings. Exploration of oil dates back to 1871 in West Java but it was not till 1883 that first successful oil well was drilled in North Sumatra and the first commercial oil field established. Since then there have been several oil discoveries, including those off-shore. Pertamina, the state-owned oil company has the sole right in oil and gas production, which is carried out mainly by a production-sharing agreement with foreign oil companies. Exploitation of geothermal reserves is being accelerated an coal production is increasing. Indonesia is the third largest producer of tin in the world. Copper is found throughout the archipelago. The are large deposits of nickel oxide, bauxite, gold, lead, manganese, silver, titanium, uranium, zinc, etc.