Greenstone is the name commonly used for the predominantly greenish-coloured rock from which the Maori made many adzes and chisels as well as a famous weapon, the patu pounamu. They also used greenstone for ornaments such as the renowned hei-tiki and ear pendants. New Zealand greenstone is either the mineral nephrite (Maori: pounamu) or bowenite (Maori: tangiwai.) Nephrite is obtained from the Taramakau-Arahura region as river boulders washed down from the parent rock in the Southern Alps; bowenite is found as beach boulders and pebbles at Anita Bay in Milford Sound. Some nephrite is also obtained from the Wakatipu region.
The value of greenstone lies in its beauty and its toughness and hardness, a result partly of mineral composition, but primarily of a characteristic felting and interweaving of minute mineral fibres. On the whole, bowenite greenstone is inferior to nephrite. The main varieties recognised by the Maori are Kahurangi — green, translucent, highly prized; Kawakawa — green, semitranslucent; Inanga — whitish, opaque; and tangiwai — translucent bowenite.
The Maoris have an interesting legend concerning the bringing of greenstone to New Zealand. Originally, it is alleged, there were two stones, Poutini (the greenstone) and Whaiapu, which belonged to Ngahue and the chieftainess Hina-tua-hoanga respectively. The latter became jealous of Ngahue's stone and drove him from Hawaiki.
Eventually his canoe, Tahirirangi, reached New Zealand and Ngahue hid his greenstone near Arahura on the west coast of the South Island. It was very well hidden and lies there to this day; however, small portions are occasionally broken off and carried down the river. These pieces provide the Maori with his source of greenstone.
From the gold workings on the west coast of the South Island much greenstone was secured, and lapidaries, both in New Zealand and overseas, found a ready sale for it as curios, at first to the Maori and afterwards to tourists and collectors. This trade has continued, but the use of greenstone by the Maori declined so rapidly that by the end of the nineteenth century its fashioning was a lost art. With the virtual cessation of gold mining, greenstone is becoming increasingly more difficult to obtain; hence, to conserve stocks and also to encourage local manufacture of imitation Maori ornaments, jewellery, and souvenirs, an embargo on the export of raw greenstone came into force in April 1947. At the present time high-quality greenstone artefacts are in keen demand as collectors' pieces and fetch high prices on the open market.
New Zealand greenstone is composed of either nephrite or bowenite, whereas the term jade is restricted to nephrite and another distinct mineral, jadeite, which is not found in New Zealand. Most New Zealand greenstone, the nephrite variety, is therefore jade.
by John James Reed, D.SC., New Zealand Geological Survey, Lower Hutt.