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