In March 2005, Brazilian miner Vale secured an exploration contract and began work on feasibility studies for an iron ore mine — a complex undertaking due to environmental concerns.

2005年3月，巴西矿业公司淡水河谷获得了一份开采合同，并开始为这家铁矿石公司提供可行性报告研究，因为环境原因这项工作很复杂。

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Ore minerals are very complex in their compositions.

矿石的矿物成分十分复杂。

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The shape of Datangpo primary manganese deposit and its ore structure are comparatively complex but the structure is simple which belongs to the sedimentary of littoral basin facies.

大塘坡原生锰矿矿体形态和矿石结构较复杂，构造简单，属滨海盆地相沉积。

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The plaintiffs claim that 11 defendants, Evraz being one, by dubious means deprived them of their majority stake in a big iron-ore complex now part of the Evraz empire.

ECONOMIST: Russian steel

The deal digs Mr Albanese out of a hole the size of Tom Price, the huge iron-ore complex in the Pilbara region of Western Australia in which Chinalco stands to take a stake.

ECONOMIST: Face value

Indeed US politicians took no notice of the development of the ORE-STEM complex that Seaborg and others supported as our only way to continual increase our living standards and wealth.

FORBES: Erskine Bowles: National Debt Threatens U. S. Innovation