The Government is proposing opening up more than 7000 hectares of conservation land to mining.
The land includes some areas in the Coromandel Peninsula, and the Inangahua sector of Paparoa National Park.
The proposal has just been released by Energy and Resources Minister Gerry Brownlee and Conservation Minister Kate Wilkinson.
Mr Brownlee said 7058ha of land presently in Schedule 4 of the Crown Minerals Act could be opened to mining, and he has floated the proposal in a discussion document.
Land in Schedule 4 is usually deemed to be of high conservation value and, at this stage, cannot be mined.
Mr Brownlee said 7058ha was just 0.2% of Schedule 4 land.
"This is nothing like the vast tracts of land suggested to date by the environmental lobby."
He said only 5% of the land being considered could actually be mined - as little as 500ha. That was smaller than the average New Zealand sheep and beef farm.
The Government is also planning to spend $4 million over the next nine months to gather information on "highly prospective" Schedule 4 land in the Coromandel and Paparoa areas as well as Rakiura National Park in Stewart Island. Non-Schedule 4 land in Northland would also be investigated for mining potential.
Documents issued with the Government's discussion paper say about $18 billion worth of minerals were estimated to be in the land to be removed from Schedule 4 in the Coromandel.
This was about a third of the $54 billion total minerals believed to be remaining in the area. Gold and silver deposits so far mined in the region have been worth more than $17 billion.
The Inangahua sector of Paparoa National Park was believed to have $1 billion to $2 billion worth of coal.
Mr Brownlee said New Zealand had an estimated $194 billion worth of minerals.
Ms Wilkinson said the Government also proposed adding an extra 12,000ha of land to Schedule 4.
The amount of land to be removed from mining protection is in line with information leaked by conservation group Forest and Bird last week. It also said this morning that 12,000ha would be added, but said it could not be seen as compensation for mining in the land to be removed.
Forest and Bird advocacy manager Kevin Hackwell said the 12,000ha had been waiting for official protection since a review in 2008.
"[It] should not be seen as trade-offs for high-value conservation land being removed from Schedule 4 because none of the expected 12,000 hectares has significant mining potential."
The Green Party said the Government was running scared from public opposition to mining, but woould not let go of the idea.
"The 500,000ha of proposed mining in protected areas has been reduced to 7000ha of mining," said Green Party co-leader Metiria Turei, .
"Despite the public backlash, John Key still doesn't get it. He wants to subsidise a further $4 million of prospecting in our protected areas."
Labour leader Phil Goff claimed the Government planned to "let the bulldozers in" to large areas of highly sensitive conservation land that National had once protected from mining in the first place.
"What they are saying is that they are planning to dig up some of the most beautiful areas of the country."
He said Labour would return any land removed from Schedule 4 back under the legislative protection from mining if it won the next election.
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