Petty, D.R. 1987 Sheet QM 240 Reinga : geological resource map of New Zealand 1:250 000. Lower Hutt: New Zealand Geological Survey. New Zealand Geological Survey report M 153. 25 p.
Abstract: The Reinga sheet area contains a limited variety of mineral types suitable for commercial development. Only a few of these have been, or are at present being exploited, partly because of the distance to potential markets. The main resource of the area is sand; high quality silica sand, mainly for glass making, is being dredged from the Parengarenga Harbour mouth, on the northern end of Kokota Spit. The extensive areas of quartzo-feldspathic sands present on the west coast of the Aupouri Peninsula have higher feldspar content and different chemical constituent ratios than those on Kokota Spit. Careful prospecting may delineate deposits suitable for alternative economic applications. Aggregate sources, although limited by the degree of weathering, appear adequate for local usage. Clay deposits have been little investigated, and have not been exploited on any large scale. Sepentinite has been quarried for a fertiliser additive and local roading from the deposit at Surville Cliffs, the largest known deposit of this material in the North Island. Serpentinised peridotite from Te Kao is used for roading. Limestone resources of the area are limited to shell deposits, and there is a small area of impure micritic limestone at Parengarenga. Northland kauri gum was the first ‘mineral’ mined in New Zealand and now, in conjunction with peat beds, will form the resource material for a new mining venture near Kaimaumau. Only small areas of coal and lignite have been located. Copper has been prospected for but to date no economic deposit has been found. Other metals, such as nickel, occur in low concentrations locally and as such do not warrant individual attention. Although the zeolite deposits may be more extensive than indicated they are not widespread, and occur only in localised tuff beds and veins. Large reserves of groundwater occur within the sand dune country along the west and east coasts, and within the alluvium of the east coast where there are areas that produce artesian water. The remaining rock types yield only limited underground water supplies.