Geological origins of pounamu
Pounamu only occurs naturally in the South Island of New Zealand. It is found in seven areas: Nelson, Westland, South Westland, Makarora (Wanaka district), Wakatipu, Milford Sound, and the Livingstone Mountains.
The two main types of pounamu are nephrite and bowenite. Both rocks form deep in the Earth’s crust and are rarer than gold. The more common nephrite is the product of high-pressure cooking of two contrasting rock types, such as dunite and greywacke.
Pounamu-bearing rocks were raised to the Earth’s surface by movement and collision along a plate boundary. They occur in the Southern Alps, which formed over the past two million years.
It is rare to find pounamu in the rock where it was originally formed. The rock is usually eroded by the action of streams, rivers, and past glaciers. This frees the pounamu, which is often discovered in rivers as boulders or pebbles, or is found washed up on the coast.
Nga putake putaiao-a-nuku
Kitea ai te pounamu i Te Wai Pounamu o Aotearoa. Kitea ai ki: Whakatu, Te Tai Poutini, Te Tonga o Te Tai Poutini, Makarora, Wanaka, Whakatipu, Piopiotahi me nga Maunga Whakatipu.
E rua nga tino momo pounamu, te nephrite me te bowenite. Hangaia ai nga kohatu e rua i te manawa o te whenua, he onge atu i te koura. Ko te nephrite he hua no te taonga tahitanga o etahi kohatu rereke e rua penei i te dunite me te onewa.
Na te oreoretanga ki te ripa tawha i hiki nga toka pounamu kia rewa ki runga i a Papatuanuku. Hangaia ai enei toka i nga maunga o Tiritiri o Te Moana i roto i nga tau rua miriona ki muri.
He uaua te kite i te pounamu i te toka o tona orokohanga. Mo te nuinga, he mea kauoro te toka matua e te wai o nga manga, o nga awa, me nga awakeo o tau ke. Na tenei i whakawatea te pounamu, a, kitea ai hei kohatu nui, kirikiri ranei i nga awa, paenga ki uta ranei i te akau.
Microscopic detail of greywacke rock. Polarised photomicrograph by N Mortimer, GNS Science.