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Critical Minerals in New Zealand

New Zealand (NZ) is home to a world class deposit of critical minerals in the form of both in situ hard rock, detrital placer gravels, and sands. These deposits are rich in minerals that are considered ‘critical minerals’ by the NZ government as they contain valuable elements including rare earth elements (REE), titanium, scandium, zirconium, and tin among other elements. These minerals are important for the advancements in clean energy, medicine, and other emerging technologies, which fuels their increasing demand.

The source of these mineral rich sands and gravels are intrusive igneous rocks outcropping within the mountain ranges west of the main divide. These tend to be in the ecologically sensitive high country and often within national parks. High levels of rainfall and erosion liberate these minerals from their host rock supplying them to rivers where they are progressively concentrated as they are transported to the ocean. During this process, the critical heavy minerals become increasingly concentrated relative to their source rocks. Deposition of these minerals forms alluvial placer deposits within the valleys and, coastal marine placer deposits along the coastline. These deposits have long been mining for gold with historic reports of valuable critical minerals being rejected with tailings.

Hard Earth Limited

Hard Earth is an Aotearoa NZ registered company prospecting the potential for REE and critical minerals on the West Coast of the South Island. Hard Earth has applied for 4 mineral permits to prospect for alluvial placers deposits in Westland. Permit locations were chosen based on geology, historic reports of enriched tailings, radiometric mapping, and previous lab results.

The source of these REE-bearing gravels is the intrusive igneous with the uplifted eastern portion of the Paparoa metamorphic core complex. These rocks have been eroded over time and washed down to form glaciofluvial and terrace river deposits which Hard Earth has applied for permits to prospect for their potential to be mined for strategic minerals.

Some of the key minerals target minerals include:

  • Monazite: A phosphate mineral that often contains significant amounts of thorium and REEs.
  • Garnet: A valuable mineral itself but has the potential to be an unconventional source for Scandium, a valuable REE
  • Zircon: A valuable Mineral used in many applications typically casting and refractory processes. It can also contain valuable REEs.
  • Xenotime: A phosphate mineral that can contain yttrium and other REE.
  • Spodumene: A lithium aluminium silicate mineral that is an important source of lithium and ceramic materials.
  • Cassiterite: A tin oxide that is the most important tin ore.
  • Other Target Minerals: Other minerals known to occur within the source rocks and alluvial deposits include sillimanite, rutile, ilmenite, and allanite.

Data from the MBIE airborne radiometric survey of Westland flown in 2013 indicates the target surface deposits enriched in thorium. Monazite is a mineral which contains elevated levels of thorium and areas that may be prospective are highlighted on the map.

Permits

Upper Buller

The Upper Buller permit application covers an area of 59.6 km2 along the Buller River and the large Inangahua River which flow into the Buller River at the Inangahua River Junction.

Maimai

The Maimai Permit application area covers 197.3 km2 situated between the Paparoa Range to the east and the Grey Valley to the west. The Paparoa National Park has been excluded from the permit and no exploration is proposed on the conservation land within the permit area.

Upper Grey

The Upper Grey permit application covers an area of 177.6 km2 along the Grey River a number of tributaries including Red Jack, Ahaura, Snowy River, and Nelson Creek.

Mount McHardy

The Mount McHardy permit application covers a 99.6 km2  area of outcropping igneous rock and contains the hard rock source for the for the alluvial deposits in the valley.

Permit Summary

The four permit areas have effectively captured much of the alluvial gravels and sand that have naturally been eroded from the mineral rich eastern side of the Paparoa Ranges and southern part of the Victoria ranges. The series of gravel terraces sloping down to the Buller River and Grey River systems, largely contained within the freehold farmlands, are largely unexplored for minerals other than gold.