Minerals

The minerals industry plays an important part in the New Zealand economy, contributing $20 million in royalties and over $1 billion in GDP per annum. 3391

New Zealand has a number of mineral resources, including gold, coal, silver and ironsand. Rock, sand and aggregate resources are also mined for construction uses.

Gold rushes occurred in the Otago, the West Coast and Coromandel regions in the 1860s. The easily accessible resources, able to be worked by individuals using simple equipment, were quickly exhausted and larger-scale mining techniques were adopted. Despite this, production of gold in New Zealand peaked in 1905. In the early 2000s, gold production in New Zealand predominately occurred at two large opencast mines at Waihi (Coromandel) and Macraes (Otago). 3392

Macres Mining (Credit: Nicola de Whit)

New Zealand has extensive coal resources, mainly in the Waikato, Taranaki, West Coast, Otago, and Southland regions. Around 80 per cent of the coal resource is lignite (low grade coal). There are 22 operating coal mines in New Zealand, three underground mines and nineteen opencast mines. 3393  In 2010, the Parliamentary Commissioner for the Environment published a report on lignite and climate change.

Click Here to see a Map of NZ coal fields

The marine environment includes large areas of relatively shallow sea underlain by plateaus and tectonic ridges that border the deep ocean basins of the Pacific Ocean and Tasman Sea. 3394  To the northeast there are volcanic arcs, including the Kermadec Arc. These areas offer significant potential as sources of minerals.

The minerals that lie under the ocean have historically been considered too difficult to extract except in shallow waters. However, as resource prices rise and deep sea technology develops, the attention paid to these minerals has dramatically increased. The excavation of phosphate nodules, seafloor massive sulphides (SMS) and manganese nodules is expected to be of increasing commercial interest within the next few years. 3395

Distribution of sedimentary basins and some mineral resources in the EEZ and ECS (Source: NIWA, 2012)

Marine Minerals

Mineral mining of New Zealand’s EEZ seabed is an emerging industry. As of August 2014, no mineral mining was being undertaken on a commercial basis within the EEZ. The Trans Tasman Resources Limited marine consent application was the first EEZ seabed mining application to be processed. In June 2014, Chatham Rock Phosphate Limited (CRP) lodged a marine consent application for phosphate mining on the Chatham Rise. These projects are discussed in further detail in the case study sections. The following table provides detail about the main mineral resources found within New Zealand’s EEZ. 

Mineral

Detal

Phosphate nodules

  • They are formed in highly productive areas of upwelling
  • The nodules are found within a 1-metre deep seabed layer consisting of fine sandy silt 3400
  • The nodules that are economically viable to recover range in size from  two to 150 millimetres
  • The phosphorite nodules are ground up, turning them into rock phosphate
  • Phosphate nodules are found on the Chatham Rise east of Christchurch at water depths of about 400 metres 3401
  • Phosphate is an essential ingredient in fertilisers, and is therefore potentially commercially valuable, particularly as the majority of New Zealand’s fertiliser is currently imported
  • Seafloor mining for phosphorite nodules is unprecedented at the moment, thus New Zealand could be the first country to permit this type of mining activity

Seafloor massive sulphides

  • These are deep undersea deposits of high grade polymetallic sulphides, rich in copper, zinc and lead, and with a high gold and silver content
  • The largest of these deposits form by mineralisation of fragmented rocks
  • Chimney-like deposits are particularly rich
  • They are produced in underwater volcanic regions, usually on seamounts, by the deposition of metals from hydrothermal fluids
  • Hydrothermal vents, which contain these minerals, have been discovered on the Kermadec Ridge off the north-east coast of the North Island of New Zealand. The location of these hydrothermal vents in the Kermadec Arc are known and mapped by researchers 3403
  • Both inactive and active vents with a low level of hydrothermal activity have the potential to be mined

Manganese nodules and cobalt crusts

  • Manganese nodules are rocky lumps found on the seabed in areas where sedimentation rates are very slow
  • They are created when manganese dissolved in seawater reacts with oxygen to create insoluble manganese oxide
  • They often contain metals such as cobalt, nickel and copper
  • Crusts that are rich in several elements, including colbalt, are found on the summits and flanks of seamounts, whereas manganese nodules are spread out over the abyssal plains and cover around 10 to 30 per cent of the seafloor
  • Some of the most extensive deposits of cobalt crusts in the world are found in the Pacific Ocean
  • Manganese nodules are abundant in an area over 250,000 square kilometre in extent, at water depths between 4000 and 5000 metres south-east of the Campbell Plateau and in the vicinity of Bollon’s Seamount, 600 kilometre south of the Chatham Islands 3405
  • The composition of nodules found within New Zealand's EEZ has been found to be relatively low in valuable metals, the value of the constituents varies with time
  • Since 2001 a number of exploratory permits have been issued by the International Seabed Authority for government institutes to survey manganese fields in areas of the deep sea outside national jurisdiction 3406

Methane hydrates

  • Are a crystalline form of methane trapped in water, occurring in continental shelf sediments in many parts of the world 3408
  • New Zealand has some large offshore gas hydrate provinces located along the east coast of the North Island and the south-west coast of the South Island 3409
  • The methane hydrates in New Zealand are found in relatively shallow water 3410
  • Research is currently underway to explore the most economical and safest way to mine methane hydrates in New Zealand 3411

Sand (including ironsand)

  • Sand extraction targets grain sizes of between 0.063 and 2 millimetres.
  • Blank iron sand contains titanomagnetite which is used for the manufacture of iron and steel.
  • Sand is used as a component of aggregate in the production of concrete and as an ingredient for other cement-based products.
  • Sand is also used to restore popular beaches.
  • New Zealand has extensive sand deposits, particularly close to major rivers.
  • In many areas, the sand is derived from land-based erosion. Sand comes from other sources, such as shell-based sands.
  • Iron sand is found along the west coast of the North Island between Kaipara Harbour and Whanganui. New Zealand Steel mines up to 1.2 million tonnes of sand each year from the north head at Port Waikato. 3413
  • Iron sand is also found offshore, in the northern and southern Taranaki bights it is present in localised concentrations of greater than 10 per cent titanomagnetite. 3414
  1. http://www.nzpam.govt.nz/cms/investors/our-resource-potential/minerals/coal

  2. http://www.teara.govt.nz/en/mining-and-underground-resources/page-2

  3. http://www.nzpam.govt.nz/cms/investors/our-resource-potential/minerals/coal

  4. http://www.gns.cri.nz/Home/Our-Science/Energy-Resources/Oil-and-Gas/NZs-Sedimentary-Basins

  5. http://worldoceanreview.com/en/wor-1/energy/marine-minerals/

  6. Ministry for the Environment, 2012, Managing our oceans: A discussion document on the regulations proposed under the Exclusive Economic Zone and Continental Shelf (Environmental Effects) Bill, Ministry for the Environment, Wellington

  7. NIWA, 2012

  8. Ministry for the Environment, 2012

  9. NIWA, 2012

  10. http://worldoceanreview.com/en/wor-1/energy/marine-minerals/

  11. http://www.straterra.co.nz/21st%20century%20mining

  12. NIWA, 2012

  13. http://www.straterra.co.nz/21st%20century%20mining

  14. http://www.gns.cri.nz/Home/Our-Science/Energy-Resources/Gas-Hydrates/Current-Research/Gas-hydrates-as-an-energy-resource

  15. http://www.nzsteel.co.nz/new-zealand-steel/the-story-of-steel/the-mining-operations/waikato-north-head-mine-site/

  16. http://www.teara.govt.nz/en/marine-minerals/page-2

Last updated at 2:03PM on February 25, 2015