The New South Wales Independent Planning Commission (IPC) has knocked back a proposal for the major expansion of an open-cut coal mine in the Hunter Valley, after a long campaign by a local Indigenous group.
Mining giant Glencore wants to extract an additional 135 million tonnes of coal over two decades at the Ravensworth mine near Singleton.
The IPC says the proposed Glendell Continued Operations project is "not in the public interest" and the removal of the nearby Ravensworth Homestead would harm Aboriginal cultural heritage values.
"The removal of the Ravensworth Homestead complex and associated heritage from the site would constitute a significant loss to future generations," the IPC said.
Wonnarua man Robert Lester said it "blew [his] mind away" when he heard the mining extension was rejected.
"We've got at least someone who's listening to us," he said.
The Plains Clan of the Wonnarua people say there was a colonial massacre at the estate in the early 1800s.
Mr Lester said the group had collected memories of atrocities that were perpetrated against members' ancestors.
"It's not something new to us, we've known about that place for years before they even started digging up coal," he said.
"Our people's bodies are scattered all over that landscape. They never got buried, they just got pushed into the ground.
"Besides all that there is heritage in that area for non-Aboriginal people as well, from the settler's days. It's got two stories to tell, that property. We're just telling the other side of the story."
Federal Greens Senator David Shoebridge said the decision was a win for Indigenous heritage and the climate change effort.
"It's a very historic day," he said.
"Fundamentally it's an extraordinary win for the Wonnarua people, who have been fighting to have their land and their culture protected from yet another monster coal mine."
'An almost impossible fight'
The IPC acknowledged social, environmental and air quality concerns could have been managed by Glencore if the expansion was approved, but said the heritage impacts were too extensive.
"Other key issues associated with the application … could be appropriately managed if the significant and irreversible impacts to historic heritage could have been avoided," it said in its statement of reasons for refusal.
"The commission could not impose conditions that in its view would appropriately manage the heritage impacts of the application."
The IPC noted the project would have created economic and social benefits as well as jobs.
Senator Shoebridge campaigned against the mine extension with the Plains Clan of the Wonnarua people for five years during his time as a NSW MLC.
"At times it seemed like an almost impossible fight up against a multinational, multi-billion-dollar mining company," he said.
"Finally that truth has begun to be heard.
"In this case it's been heard by the IPC.
"This site of frontier war and frontier resistance will actually be protected."
Wonnarua people are the traditional custodians of the Hunter Valley, which has 41 coal mines.
Mr Lester said the determination had "opened a Pandora's box for us" and given them confidence traditional owners could influence decisions about mining developments.
'Disheartening' decision: Miner
Glencore said it was disappointed with the IPC's decision and would consider further action.
"It is particularly disheartening considering that Glencore has invested more than six years and $25 million in studies as well as consulting with the community to produce a viable and environmentally sustainable project," it said in a statement.
"The project would have provided jobs for up to 600 people and ongoing support for 350 businesses in the Hunter region.
"We will carefully review the IPC's determination and statement of reasons and then decide if any further course of action is required."
The ABC requested an interview with Glencore, but the company declined.
The NSW Minerals council has slammed the IPC for rejecting the Glendell extension, pointing out that at least two thirds of the public submissions it received about the project were in support.
It said the project would have secured nearly 700 jobs, delivered over $500 million in capital investment and provided well over $300 million in royalties to the people of NSW.
The council was critical of the three-person IPC panel and said it was not being held accountable to the NSW government and the public.