Between $1.9 billion and $2.2 billion of this amount will be impairments for current mines and development projects, advanced exploration projects, including those in Canada, and deferred projects including its Avebury nickel mine in Tasmania.
Between $200 million and $300 million of the writedowns relates to negative mark-to-market adjustment of listed equity investments including uranium explorer Toro Energy Ltd and metals processor Nyrstar.
The same amount will be attributed to derecognition of deferred tax assets in respect of tax losses.
"As a consequence of the significant falls in commodity prices seen across all of our operations, the carrying value of many of our assets has declined considerably," chief financial officer David Lamont said.
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