Latitude & Longitude (WGS84):	37° 15' 4'' South , 175° 41' 44'' East
Latitude & Longitude (decimal):	-37.25135,175.69564
GeoHash:	G#: rckun49ej
Köppen climate type:	Cfb : Temperate oceanic climate

Historic gold mine.

Active from 1897 until around 1908. The Energetic is first mentioned in 1897, by prospectors Laurie and Stevenson (surnames). By 1899, the lease is under the name of Sheet Anchor, with J. Newdick, and John Thomas James Tilsley, brother D. Tilsley, sinking winzes onto the reef and driving a tunnel which ran under the reef and missed it due to its flat lying nature. The Capstan lease is also owned by this group. The Sheet Anchor lease achieves from 1899 to 1903 38 tonnes of ore for 465 ounces of gold. Meanwhile the We Three lease achieves 2 tonnes of ore for 92 ounces of gold by 1903.

Around 1903 an English syndicate called the Sheet Anchor Gold Mining Company takes over the Sheet Anchor lease, driving a tunnel 1400 feet which also misses the reef. A two stamp battery had been erected, described as steam powered and equivalent to a ten stamp normal battery. An aerial tramway is also erected. They abandon the property when their capital was exhausted.

In 1905, the Omahu Mines Limited is formed to take over several leases including We Three, Capstan, and Sheet Anchor at 250 acres in total. A five stamp battery is mentioned at this stage. The Omahu Company had 200 tonnes of ore at grass, and in 1906 the first crushing was still to take place. They abandon the property in 1907. In 1908, the Last Shot syndicate extracts 150 tonnes of ore from the We Three lease. When inspected in 1912, the mine had been abandoned, the battery removed, and the workings collasped. Between 1905 to 1908 the Omahu company mine had produced 836 tonnes of ore yielding 845 ounces of gold.

The country rock is andesite, with rhyolite tuff capping. At We Three there is with one vein trending north-east, 8-12 inches wide. Payable ore was found in the upper oxidised zone, which was much crushed and disjointed, partly recemented, and mixed with limonite infused clays. At the Sheet Anchor, the reef was historically described as flat, rubbly, 3-5 feet wide, with clay containing hard blocks of quartz with visible gold associated with un-named silver sulphides, and siliceous matter. The quartz was finely granular with rust stained cavities and joint planes, with patchy silver sulphides, and very fine gold. The vein is in ryholite tuff near its contact with andesite.

Historically the mines were said to be on the northern ridge above the two branches of the Omahu Creek, and two miles east of the Omahu Station (main highway). The Mindat co-ordinates are very approximate. The area is now thickly forested and difficult to access.

Mineral List

2 valid minerals.

Rock Types Recorded

Regional Geology

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

Quaternary 0 - 2.588 Ma ID: 3187411	Cenozoic volcanic rocks Age: Pleistocene (0 - 2.588 Ma) Lithology: Ignimbrite(s); felsic volcanic rocks; rhyolite 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. [154]
Pliocene - Late Miocene 2.588 - 11.62 Ma ID: 1308439	Whitianga Group rhyolite lava and related deposits Age: Neogene (2.588 - 11.62 Ma) Stratigraphic Name: Whitianga Group Description: Rhyolite lavas and dome complexes with associated breccia and tuff; minor obsidian and intense hydrothermal alteration locally. Comments: Zealandia Megasequence Extrusive and Intrusive Rocks (Neogene) Lithology: Rhyolite, breccia, tuffite 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. [12]
Messinian - Tortonian 5.333 - 11.62 Ma ID: 1332879	Coroglen Subgroup ignimbrite (Whitianga Group) of Coromandel Volcanic Zone Age: Miocene (5.333 - 11.62 Ma) Stratigraphic Name: Coroglen Subgroup Description: Ignimbrite flow sheets and local rhyolitic and obsidian-rich pumice breccia deposits and tuff. Comments: Neogene igneous rocks. Age based on K-Ar and FT Lithology: Major:: {ignimbrite},Minor:: {rhyolite, tuff, breccia} Reference: Heron, D.W. . Geology Map of New Zealand 1:250 000. GNS Science Geological Map 1. [13]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References