The main classifications are kawakawa, kahurangi, ?nanga, and tangiwai. The first three are nephrite jade, while tangiwai is a form of bowenite.
?nanga pounamu takes its name from a native freshwater fish (Galaxias maculatus) and is pearly-white or grey-green in colour and varies from translucent to opaque.
Kahurangi pounamu is highly translucent and has a vivid shade of green. It is named after the clearness of the sky and is the rarest variety of pounamu.
Kawakawa pounamu comes in many shades, often with flecks or inclusions, and is named after the leaves of the native kawakawa tree (Macropiper excelsum). It is the most common variety of pounamu.
Tangiwai pounamu is clear like glass but in a wide range of shades. The name comes from the word for the tears that come from great sorrow.
In modern usage pounamu almost always refers to nephrite jade. Pounamu is generally found in rivers in specific parts of the South Island as nondescript boulders and stones. These are difficult to identify as pounamu without cutting them open.
Significance to M?ori
A wide range of pounamu objects
Pounamu plays a very important role in M?ori culture. It is considered a taonga (treasure) and therefore protected under the Treaty of Waitangi. Pounamu taonga increase in mana (prestige) as they pass from one generation to another. The most prized taonga are those with known histories going back many generations. These are believed to have their own mana and were often given as gifts to seal important agreements.
Pounamu taonga include tools such as toki (adzes), whao (chisels), whao whakak?ka (gouges), ripi pounamu (knives), scrapers, awls, hammer stones, and drill points. Hunting tools include matau (fishing hooks) and lures, spear points, and k?k? poria (leg rings for fastening captive birds); weapons such as mere (short handled clubs); and ornaments such as pendants (hei-tiki, hei matau and pekapeka), ear pendants (kuru and kapeu), and cloak pins. 
Functional pounamu tools were widely worn for both practical and ornamental reasons, and continued to be worn as purely ornamental pendants (hei kak?) even after they were no longer used as tools.
Pounamu is found on the West Coast, Fiordland and western Southland.
It is typically recovered from rivers and beaches where it has been transported to after being eroded from the mountains. However, pounamu has also been quarried by M?ori from the mountains, even above the snow line. The group of rocks where pounamu comes from are called ophiolites. Ophiolites are slices of the deep ocean crust and part of the mantle. When these deep mantle rocks (serpentinite) and crustal rock (maficigneous rocks) are heated up (metamorphosed) together, pounamu can be formed at their contact.
Pounamu has been formed in New Zealand in three main locations. The Dun Mountain Ophiolite Belt has been metamorphosed in western Southland and pounamu from this belt is found along the eastern and northern edge of Fiordland. The Anita Bay Dunite near Milford Sound is a small but highly prized source of pounamu. In the Southern Alps, the Pounamu Ultramafic Belt in the Haast Schist occurs as isolated pods which are eroded and found on West Coast rivers and beaches.
Jewellery and other decorative items made from gold and pounamu were particularly fashionable in New Zealand in the Victorian and Edwardian years in the late 19th and early 20th century. It continues to be popular among New Zealanders and is often presented as gifts to visitors and to New Zealanders moving overseas. In 2009 David Anthony Saxton and his son Morgan David Saxton were sentenced to two and a half years imprisonment for stealing greenstone, with a helicopter, from the southern West Coast.
Viggo Mortensen, Aragorn in The Lord of the Rings, took to wearing a hei matau around his neck. Michael Hurst of the television programme Hercules was given a large and heavy pounamu pendant necklace which he wore on the programme. During a particularly energetic action scene the pendant bumped his teeth. The producers felt the ornament suited the nature of the programme yet considered it a safety risk, and had it replaced with a latex replica.
In the 2016 animated movie Moana, Te Fiti's heart was a pounamu stone.
Maori woman with kiwi feather cloak and hei-tiki pendant.
Maori chief holding a mere.
Maori woman with tattooed chin wearing a pekapeka pendant.
Hinepare, a woman of the Ng?ti Kahungunu tribe. She is wearing a pounamu hei-tiki around her neck, and one pounamu earring and one shark tooth earring
Ear pendant (pekapeka), Maori people, pounamu and red sealing wax
Kataore, Mere pounamu (42 cm x 12 cm) named after a Ng?i Tahu chief killed by Te Rauparaha in the 1830s. Gifted by Riwai Keioni Te Ahu, Te Ati Awa to Sir George Grey.
A portrait of Wahanui Reihana Te Huatare, carrying a mere and wearing a heitiki made of pounamu
A portrait of Rangi Topeora, wearing numerous pounamu items.
Nephrite pounamu hei-tiki
A kuru (straight earring). Kapeu are similar, but with curved ends, and are also used as teething aids.
A k?k? p?ria, a bird leg ring used to fasten decoy birds used in hunting.
^Coombs, D. S.; Landis, C. A.; Norris, R. J.; Sinton, J. M.; Borns, D. J.; Craw, D. (1976). "The Dun Mountain ophiolite belt, New Zealand, its tectonic setting, constitution, and origin, with special reference to the southern portion". American Journal of Science. 276 (5): 561-603. doi:10.2475/ajs.276.5.561. ISSN0002-9599.
^Coutts, P. J. F. (1971). "Greenstone: the prehistoric exploitation of bowenite from Anita Bay, Milford Sound". The Journal of the Polynesian Society. 80 (1): 42-73.
^Cooper, A.F.; Reay, A. (1983). "Lithology, field relationships, and structure of the Pounamu Ultramafics from the Whitcombe and Hokitika Rivers, Westland, New Zealand". New Zealand Journal of Geology and Geophysics. 26 (4): 359-379. doi:10.1080/00288306.1983.10422254. ISSN0028-8306.
^"Pounamu - a special gift". Kura Pounamu Treasured stone of Aotearoa New Zealand. Museum of New Zealand Te Papa Tongarewa. Retrieved 2010.