|Latitude & Longitude (WGS84):||37° 23' 4'' South , 175° 51' 29'' East|
|Latitude & Longitude (decimal):||-37.38453,175.85814|
|Köppen climate type:||Cfb : Temperate oceanic climate|
The Correnso vein was discovered in 2009, under the eastern section of Waihi, and under a kilometre southeast of the Martha Mine (Waihi Mine) open pit. Oceanagold Gold began mining the deposit in 2015, directly below the housing on the eastern side of town. The mine and its associated mineralised vein is named after corrensite, a relatively uncommon clay mineral found at depth in the deposit.
The vein trends north-south, as an Au-Ag rich low sulphidation epithermal deposit, hosted by variably altered Miocene aged andesite of the Waipupu Formation. Vein mineralisation includes pyrite, sphalerite, galena, chalcopyrite, with gold-silver found in electrum as inclusions within the base metal sulphides. Breccia zones occur in the upper part, proximal to the mineralised veins. Alteration consists of quartz-chlorite-adularia-sericite-calcite-pyrite.
There is a main Correnso vein, with two smaller sub- parallel veins called Correnso West and Correnso East. The veins dip moderately to steeply east. The northern section is more faulted and fractured. Quartz, calcite, chlorite, various clay species, pyrite dominate the assemblage.
Ignimbrite occurs near surface. This and the upper levels of the andesite are variably weathered and oxidised with limonite common. Clay alteration is common in the andesite, with variable colours, and including nontronite, montmorillonite, kaolinite, dickite, alunite, saponite, illite, smectite, tosudite, rectorite, and corrensite. The last three are reasonably uncommon on Mindat if clays are your thing. Vermiculite is also found in a clay form, distal to the main vein in the upper parts.
While pyrite occurs as veinlets and disseminated through much of the deposit, the other base metal sulphides tend to increase with depth. Magnetite is found associated with galena and pyrite, while ilmenite is found proximal to the mineralised veins. Pyrite is found as veinlets, with yellowish cubic crystals dominant. Chalcopyrite comes as disseminated grains, and isolated stronger yellow crystals associated with sphalerite and galena. Sphalerite is mostly poorly shaped irregular dark grey to brownish grey crystals, associated with galena and chalcopyrite. Galena is found only within the veins, associated with sphalerite and pyrite. Gold is found within electrum, as inclusions within the base metal sulphides.
The mineralisation is found in quartz-calcite veins. The quartz is found as crystalline, colloform, crustiform banding, and as groundmass filling gaps and voids, coloured white, pale grey, or light yellow. The quartz is commonly associated with muscovite which forms an enveloping blanket around the veins, with minor chlorite, calcite, and albite. Calcite is common as platy or bladed shaped crystals in veins, intergrown with quartz, corrensite and chlorite. Calcite increases with depth. Photographs of drill cores indicate minor amethyst at depth, possibly with amethyst margins and white quartz central areas of the vein. Cristobalite and tridymite are noted distal to the veins.
Zeolites are noted by (Singh, 2015) in shallow levels, and distal to the ore body, but remain un-named, and not studied to any degree.
22 valid minerals.
Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
0 - 2.588 Ma
|Cenozoic volcanic rocks|
Age: Pleistocene (0 - 2.588 Ma)
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
|Late Pleistocene - Middle Pleistocene|
0.0117 - 0.781 Ma
|OIS5+ (Early Pleistocene - Middle Pleistocene) river depoists|
Age: Pleistocene (0.0117 - 0.781 Ma)
Stratigraphic Name: Matua Subgroup
Reference: Heron, D.W. . Geology Map of New Zealand 1:250 000. GNS Science Geological Map 1. 
|Early Pliocene - Late Miocene|
3.6 - 11.62 Ma
|Coromandel Group Pliocene andesite and basaltic andesite lava|
Age: Neogene (3.6 - 11.62 Ma)
Stratigraphic Name: Coromandel Group
Comments: Zealandia Megasequence Extrusive and Intrusive Rocks (Neogene)
Reference: Edbrooke, S.W., Heron, D.W., Forsyth, P.J., Jongens, R. (compilers). Geology Map of New Zealand 1:1 000 000. GNS Science Geological Map 2.