Because of its diverse geology and dynamic tectonic history, New Zealand had a wide variety of potentially profitable mineral deposits, although few have been extensively exploited. Mining was a leading industry in 2002, and gold continued to dominate the mining sector. The mining industry contributed 1% to GDP in 2001, with another 2%–3% provided by the mineral processing sector. The main exports were ironsand, halloysite clay (for the manufacture of high-quality ceramics), limestone, cement, salt (by solar evaporation of seawater), sulfur, and pumice. Most output of industrial minerals was for domestic use, because the distances to overseas markets limited most exports to the high-value commodities or products with unique applications or specifications.
Gold production for 2001 was 10,000 kg, from two large hard-rock mines—the Martha Hill, at the base of the Coromandel Peninsula, at Waihi, southeast of Auckland, and the Macraes, north of Dunedin—as well as alluvial gold from three dredging operations on South Island. The Macraes Mine, which accounted for more than 50% of the country's production, received approval for expansion of throughput to 4.5 million tons per year, having successfully commissioned pressure oxidation autoclaves for treating refractory ores; it was to absorb 65,000 tons per year of concentrate from the new Globe-Progress Mine, which was planned to mill 1 million tons per year. In addition, the Reefton Goldfield, which closed in 1951, was expected to pour gold again in 2002.
In 2001, 2.7 million tons of ironsand (titaniferous magnetite) was extracted and exported to Japan. Iron ore in the form of titanomagnetite-rich sand derived from the coastal erosion of the Mount Taranaki volcanics was mined from beach and dune sands, concentrated at two sites along the western coast of North Island. Although the existence of large quantities of iron-bearing sands has been known for more than a century, the steelmaking industry was not able to exploit them until the late 1960s.
Silver mine output in 2001 was 23,000 kg. Output of building materials in 2001 included 7.5 million tons of sand and gravel for building aggregate, and 550,000 tons of limestone for roads. New Zealand also produced bentonite, clays for brick and tile, diatomaceous earth (which included zeolite), dolomite, kaolinite (pottery), lime, marl, marble, nitrogen, perlite (which included zeolite), quartzite, rock for harbor work, salt, sand and gravel (including silica [glass] sand and amorphous silica), serpentinite, and dimension stone. Considerable potential for platinum and platinum-group metals from hard-rock deposits and alluvial concentrations existed, the most promising area being the Longwood Range, in western Southland. Uranium-bearing minerals have been located on the South Island.
State-owned "Crown minerals," based on the British legal system, were owned and regulated by the New Zealand Crown Minerals Act 1991 and the Crown Minerals Amendment Act (No. 2), passed in 1997. Crown-owned minerals included all naturally occurring gold, silver, and uranium; substantial amounts of coal; other metallic and nonmetallic minerals and aggregates; and all petroleum. Minerals not designated as Crown owned were privately owned. New Zealand has not enacted native title legislation to gain access to Maori lands, claims for which were handled through the Treaty of Waitangi Tribunal.
Gold was discovered in New Zealand in the early 19th century when European sealers and whalers were first exploring the country. The mining industry began in 1852, upon the discovery of hard-rock gold on the Coromandel region, North Island, by European settlers. Gold deposits were discovered on the South Island in 1861. By 1870, copper, iron, lead, and silver deposits had been discovered and worked, and deposits of antimony, arsenic, chromium, zinc, and other minerals had been located. After World War II, industrial minerals, aggregate, and stone production grew steadily, coal mining fluctuated, and gold output declined. Extensive exploration in the 1950s and 1960s found natural gas and gas condensate, ironsand, and geothermal energy.