Government papers show there is at least $50 billion worth of minerals beneath Kahurangi National Park, which covers the north west corner of the South Island.
The minerals include zinc, copper, nickel and tungsten.
This information is in papers prepared by the Ministry of Economic Development for Energy and Resources Minister Gerry Brownlee, and Conservation Minister Tim Groser.
In a speech in August, Mr Brownlee called for a stocktake of the country's mineral potential, including that underneath conservation land.
The ministry advice also mentions coal deposits in Westland's Paparoa National Park, precious metals in Coromandel and petroleum under Waitutu Forest.
Their total value is estimated at $240 billion.