By Adria Calatayud
Rio Tinto PLC said Friday that ore reserves decreased at its Argyle diamond mine in Australia and Boron borates operations in California, and increased at its Pilbara iron ore operations in Australia.
The miner also said that ore reserves at its Simandou project in Guinea have been downgraded fully to mineral resource, due to uncertainties on the development of the project under future ownership. Rio Tinto agreed to sell its stake in the project to Aluminum Corp. of China Ltd. (>> company sheet) in 2016.
Rio Tinto cut its estimated Argyle ore reserves by 13 million tons to 16 million tons, and said that it has written back mineral resources at the site, since mineralized deposits don't demonstrate economic prospects and aren't scheduled for production.
The company's Boron ore reserves have decreased by 6 million tons to 16 million tons, which has resulted in an increase in mineral resources to 8.5 million tons from zero, Rio Tinto said.
Meanwhile, at Rio Tinto's operations in the Pilbara region of western Australia, the company increased estimated iron ore reserves by 165 million metric tons, while estimated mineral reserves rose by 508 million tons.
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