The last remaining member of Mineral Resources’ ethics committee has quit the iron ore and lithium miner’s board just a week after the exit of two other directors, leaving the Perth-headquartered company in crisis.

The abrupt resignation of Denise McComish on Wednesday follows the departures of Jacqueline McGill and Susie Corlett. The three directors were privately the most critical of Chris Ellison, founder and managing director of the loss-making miner.