Te Ahumata (White Cliffs), Great Barrier Island, Auckland Region, New Zealandi

Regional Level Types
Te Ahumata (White Cliffs)	- not defined -
Great Barrier Island	Island
Auckland Region	Region
New Zealand	Country

Silver with some gold was found in the southern part of the island in 1893 alternatively known as Te Ahumata or White Cliffs, centred on a large grass covered mountain near Whangaparapara. Until 1908 about 1300 kg of silver/gold bullion was produced.

The discoverers were the Sanderson brothers early 1893, showing a lode trending east-west, dipping south, 2-6 feet wide. It was hosted in country rock of soft blue to whitish sandstone, the lode including a 2 foot wide kaolin seam along the Footwall. Several more lodes were subsequently uncovered in the surrounding area.

It appears during much of the 1890's mining was restricted to prospectors, and small companies with limited capital, covering a range of leases. In 1897, named leases included Mount Argentum, the Great Barrier Excelsior formerly known as White Cliffs, Aotea, Bonanza, Comstock, Junction Barrier, Silver King, Great Barrier Eastern, Great Barrier East. From this time the Great Barrier Gold and Silver Estates Company began consolidating leases, and from 1899 constructed a 20 stamp battery, opening in 1900 and lasting until 1908.

Then no mining took place until 1971 when Consolidated Silver Mining Company quarried 900 tonnes of quartz from the Iona section. Several companies and individuals explored the area until the mid 1980's. A comprehensive study of the deposits is potentially lacking, and any exploration even purely scientific in nature, may meet local opposition, for fear it will lead to mining. Indications are the deposits are complex containing base metals, sulphosalts, seleniferous and selenide minerals and stibnite.

Mineralisation is found in quartz veins in hydrothermally altered Miocene andesites, caped by silicified late Miocene-Pliocene rhyolitic pyroclastic rocks and volcaniclastic sediments. Early alteration resulted in adularia-illite, followed outwards by illite-smectite, and distal Ca smectite.

Silver is found as small quantities of native silver, much chlorargyrite which initially is creamy white however on exposure to air turns purple then black, and pyragyrite. Silver selenide minerals naumannite and aguilarite are found, and many of the lodes contain much stibnite. Galena, sphalerite and chalcopyrite is found at depth. Also mentioned is pyrite, electrum, tetrahedrite, trace pyrrhotite. Species listed under Lees Reef are also possible for neighbouring areas.

Since mining has stopped the lode has gained almost mythical status with comments like a mountain of silver worth billions of dollars being bandied about with little supporting evidence. It is assumed if such a treasure remained mining would not have stopped in 1908, or at least mining would have resumed shortly after.

Plans to allow exploration work in 2010 drew considerable opposition from the local community.

The Mindat co-ordinates are the site of the battery remains. Various tunnels are said to be hidden in the surrounding scrub.

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References