Rio Tinto crashed to a $US3 billion loss in 2012, on the back of the $14.4 billion writedowns of its aluminium and coal businesses that cost former Rio boss Tom Albanese his job.

And although the paper loss was well flagged to the market, the Rio results released this afternoon also showed just how much its iron ore division was crunched by the sharp crash in commodity prices in the middle of last year.

Despite Rio chairman Jan Du Plessis saying the company had "performed well" in the circumstances, Rio's underlying earnings dropped 40 per cent from $US15.5 billion in 2011 to $US9.3 billion last year.