OceanaGold has sought a mining permit over its Wharekirauponga discovery in the Coromandel Forest Park.
The deposit lies in the northern part of the 3,762 square-kilometre Hauraki exploration permit the company and its predecessors have worked since 2003. It is about 10 kilometres north of the firm's Martha Pit in Waihi.
OceanaGold says the deposit's location in the forest park rules out surface mining. But it believes there is potential to tunnel from outside the forest park and carry out any processing at Waihi.
"This project presents opportunities for the region in addition to our operation at Waihi, sustaining an industry that is a significant long-term contributor to the region and the broader economy," says Kit Wilson, OceanaGold's senior community advisor.
After 15 years of exploration "the next step is to apply for a mining permit and conduct technical, social, cultural and environmental studies that will tell us what that underground mine might look like and whether mining is going to be acceptable in that location."
The firm's application, lodged with New Zealand Petroleum & Minerals, comes a week after Minister Eugenie Sage, who holds the conservation and lands portfolios, effectively blocked further expansion of OceanaGold's Waihi operation by stopping the company buying land for a future tailings dam.
The Labour-led government has also banned any new mining on Department of Conservation land.
ASX-listed OceanaGold believes its approach, by entering the area underground and from outside the conservation estate, should meet the objectives of the government's ban.
The company, which also operates the Macrae's Mine near Dunedin, produced 83,500 ounces of gold at Waihi last year and is aiming for 60-70,000 this year.
It employs about 360 miners and contractors at Waihi, where the average mine salary is about $120,000. The town and its surrounding areas have a population of about 6,600, according to the district council.
In February, Oceana said drilling showed a high-grade mineral resource at Wharekirauponga. An indicated resource of 410,000 tonnes of ore in one vein may deliver 234,000 and 296,000 ounces of gold and silver respectively, the company said at the time.
Inferred resources could add another 1.05 million tonnes of ore containing 401,000 ounces of gold and 568,000 ounces of silver.
Oceana says the gold in the area lies in a quartz vein up to 9 metres wide at depths down to 450 metres. It says the deposit is typical of other high-grade resources discovered in Hauraki.
Wharekirauponga was previously mined late in the 19th century. Exploration resumed in the late 1970s. Oceana acquired its interest in the area when it purchased Waihi mine operator Newmont Mining in 2016.
Oceana said about $25.7 million has been spent on exploration in the area since 2010. Another $50m could be spent in coming years investigating the potential for mining.
No mining can be undertaken without resource consent. Further studies will be required to test the feasibility of the proposal and they will also require consents.
Access to the conservation estate would remain at the discretion of the Department of Conservation, Oceana noted. The current access agreement covers 428 hectares.
"An application for resource consents to mine at Wharekirauponga in the future would happen in close consultation with iwi and all affected communities under the Resource Management Act," Wilson said.