The rocks of New Zealand can be grouped into three main
elements: the Early to Mid Paleozoic Western Province, Late Paleozoic to Early
Cretaceous Eastern Province, and several overlying Late Cretaceous to Cenozoic
sedimentary basins. The Western and Eastern provinces were formed on or near the
margin of Gondwanaland, whereas the Late Cretaceous to Cenozoic sedimentary
basins developed after the separation of New Zealand from Gondwanaland in the
Late Cretaceous.

The Early to Mid Paleozoic Western Province rocks are
exposed in Nelson, Westland and Fiordland and include metamorphosed sandstone,
mudstone, limestone, and volcanic rocks, intruded by granite batholiths and
maficultramafic igneous complexes. The main associated mineral deposits are
gold-quartz lodes hosted by Paleozoic greywacke and argillite. Other type of
deposits present include: volcanogenic massive sulphide lead-zinc; vein and
greisen tungsten and tin; and magmatic nickel-copper sulphide, platinum group
element, and magnetiteilmenite deposits. Granite stocks and batholiths, intruded
during the Cretaceous, have associated porphyry molybdenum deposits.

The Late Paleozoic to Early Cretaceous Eastern Province
includes the greywacke rocks forming the axial ranges of the North and South
islands, and a belt of schists in Marlborough, the Southern Alps and Otago. The
schists host many shear-zone related, gold-quartz lodes and, in the Southern
Alps, lenses of serpentinite with talcmagnesite and nephrite jade. Volcanogenic
massive sulphide copper deposits and volcanogenic manganesechert deposits, occur
in both the schist and greywacke, and a belt of Permian age ultramafic rocks
(Dun Mountain Ophiolite) has associated copper, chromite and chrysotile asbestos
deposits.

The Late Cretaceous to Cenozoic rocks are found in a number
of sedimentary basins onshore and offshore of the North and South Islands. Many
of these basins developed during the rifting of New Zealand from Gondwanaland in
the Late Cretaceous. They contain New Zealand's economic petroleum, coal and
limestone deposits. Uplift and erosion of the mountain ranges shed gold into
rich placer deposits in the South Island.

From the Miocene, volcanic rocks
feature prominently on the eastern South Island (e.g. Banks Peninsula southeast
of Christchurch and the Otago Peninsula northeast of Dunedin) and northern North
Island (Northland and Hauraki), and volcanism continues today in the Taupo
Volcanic Zone. The North Island volcanic rocks have associated epithermal
mineralisation, mainly gold and silver, but also copper, lead, zinc, mercury,
and antimony, as well as deposits of sulphur, perlite, pumice and zeolite.
Porphyry copper style mineralisation is associated with subvolcanic intrusive
rocks. Erosion of the volcanic rocks has shed titanomagnetite onto the west
coast of the North Island forming significant coastal placer deposits.
Similarly, erosion of the Alpine schists in the South Island has resulted in
placer ilmenite deposits on the coast of Westland.