The accident happened at the OceanaGold mine near Reefton, 79km northeast of Greymouth, when the truck was reversing up to a bank to empty its load and tipped down the bank, a Summit Rescue Helicopter spokesman said.
The bank was as high as a two-storey building and the truck ended up on its back.
The 51-year-old driver, from Reefton, was held in his seat by his seatbelt and suffered head and neck injures. He was treated at the scene by St John paramedics and flown to Greymouth Hospital.
Melbourne-based OceanaGold is among the four biggest Australasian-based gold producers and its Reefton mine is a major goldflied. It is a conventional open pit operation.
The land is administered by the New Zealand Department of Conservation and is included in the Victoria Forest Park. The terrain is steep and inaccessible.
