Mineral Resources said its Carina mine could be closed down if the iron ore price continues its free fall.
Managing director Chris Ellison said it would be forced to “turn off the tonnes” should the price retreat further.
"If it gets to a point where it is below our cash costs we would turn off," Ellison told SMH.
"That is not too far away from where we are now."
Carina mine has produced more than 7.7 million tonnes of iron ore since opening in December.
The company has already moved to wind up the older Phil's Creek and Spinifex Ridge mines.
Mineral Resources also owns several mine service companies including Crushing Services International and Process Minerals International but said these businesses have been somewhat shielded as they hold contracts with major iron ore players.
The price of iron ore has crashed by 50 per cent since the start of the year to trade at just $US70 a tonne.
Mineral Resources chairman Peter Wade said at this price “at some sites we are balance sheet positive and on others we are balance sheet negative".