The world has plenty of potash 610 years worth, which ensures centuries more of fertilizer-making, and 590 years of known iron-ore reserves, according to U.S. Geological Survey estimates.

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Reserves of ore or a mineral.

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Rinehart inherited or has acquired the rights to some of the largest mineral leases in the Pilbara, believed to contain billions of tons of minable reserves of iron ore.

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Rio Tinto (nyse: RTP - news - people ), based in London, is one of the most diversified mining companies in the world, with huge reserves of iron ore, copper, aluminum and uranium.

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Reserves are all the ore we know exactly is out there.

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Back on land, mining-company engineers say new techniques, such as dissolving minerals and sucking them up through a pipe or extracting ore with high-powered water jets, could increase recoverable reserves.

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Guinea has a third of the world's bauxite reserves, as well as gold, diamonds, iron ore and vast hydroelectric potential.

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Sure, they dig up the ore as well, but a goodly part of the industry involves itself with checking resources so that they become reserves.

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Sesa Goa has extractable reserves of around 200 million tons in three Indian states and sold close to 10 million tons of iron ore in the fiscal year that ended in March.

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