In August, Mr Brownlee said the Government would undertake a stocktake of mineral resources in conservation land, protected under schedule four of the Crown Minerals Act.
The estimated value of untapped minerals has been put at about $140 billion and around 70 percent of that involved conservation land.
"We certainly have no intention of digging up the Crown's conservation estate. This is a stocktake, which is perfectly reasonable," Mr Brownlee said at the time.
Mr Brownlee told Radio New Zealand today that there were areas of interest in the Coromandel.
"There are interesting areas in the Coromandel, and it will be controversial me even saying it, where there could be -- and I stress could be -- further gold mining activity," he said.
"I doubt it would be above ground, where those areas deemed to have relatively low conservation values but are currently locked up because they are deemed to have high values."
Coromandel Watchdog was involved in ending mining on the peninsular 20 years ago. Spokesman Denis Tegg told Radio New Zealand his group would fight the move. Land now considered lower value was regenerating and becoming more special as it was allowed to recover.
Mining would be devastating, he said.
"The experience we have from overseas and in some cases in New Zealand is that those tailings (toxic waste) cannot be contained forever."
The Greens say the value of the land for recreation and tourism was far greater than income from mining.
The party previously released figures showing there were 21 current mineral permits for prospecting and exploration, affecting 42 protected areas.
Mining companies have welcomed the stocktake and say mitigation work can be done in mined areas.
