Dunite was first identified and named by the German geologist Hochstetler, after visiting Dun Mountain near Nelson, Aotearoa NZ in 1859. This mountain range has a dun colour originating from the natural weathering of the exposed ultramafic rocks that oxidises the iron while the high levels of magnesium and other elements stunt plant growth.
A belt of dunite and other ultramafic rocks run the length of Aotearoa from Southland, to Ahipara Bay in Northland, known as the Dun Mountain Ophiolite Belt. The belt is around 10 km wide and estimated to be 30-40 km in depth Much the belt is buried beneath surface, but at times exposed, particularly in the Dun Mountain range near Nelson at the top of the South Island, in Southland at the bottom of the South Island and in Red Mountain, Fiordland. In addition to the ophiolite belt, a belt of ultramafic igneous rocks are exposed along the South Coast of the South Island known as the Brook Street Terrane.
The magnesium rich minerals olivine and serpentine, contained within this belt of ultramafic rocks, are very well suited for carbon sequestration via mineral carbonation. These rock types and minerals are being investigated by a number of academic and industry organisations worldwide, for combination with both direct air capture technologies (DAC) and point source emissions (carbon capture and storage CCS).
The geologically active setting present in Aotearoa continuously exposes fresh ultramafic rocks and these, being fresher, and are more chemically reactive for CO2 sequestration than the older more deeply weathered ultramafic rocks found in other tectonically quiet countries such as Africa and the Middle East.
Following four years of investigation, Weora Limited in 2021 lodged five Prospecting Permit Applications with NZP&M, for areas containing a total of 1,281 square kilometres. Whilst the majority of these deposits are buried from the surface, four significant South Island deposits are found near or at surface. In the North Island deposits are with one exception being a site at Wairere, all are sub-surface.
Our Greenhills prospect, 10 kms from the Bluff port and Tiwai Aluminium Smelter is that target of our initial drilling campaign. 100 kms NW at Mossburn a mountain range of Dunite rocks covers a large area. The Manapouri Hydro power lines to Bluff power pass conveniently close to this location. The third deposit at Red Hills in contained within the Fiordland national Park and mining is forbidden, whilst the fourth deposit at Mt Dun at the top of the South island is in close proximity to the Nelson port and the many heavy industries, particularly timber. In the North island, deposits are generally buried at depth. Aotearoa’s last remaining coal fire power station at Huntly, south of Auckland, where the deposits are circa 600 metres beneath the surface, easily drillable.