Birthday Reef’s gold-

Birthday Reef’s gold-bearing quartz a job creator

More than 70 years after it was last worked, miners have finally reached the rich Birthday Reef beneath old Waiuta township, south of Reefton.
Federation Mining’s tunnelling reached the gold-bearing quartz reef at the weekend, meaning staff can now touch the deposits.

Birthday Reef has not been worked since July 1951, when there was a major collapse in the original Blackwater shaft. Soon after, the company’s London-based board of directors decided to abandon the mine. With no alternative employment in the area, within just a few weeks many miners and their families had abandoned Waiuta, and a few months later it was almost a ghost town.

A couple of years ago Australian-owned Federation Mining began tunnelling in from the nearby Snowy River side, aiming for the famed reef.

“Over the weekend our team developed on to the Birthday Reef,” the company said in an update on Monday.

“This is an exciting milestone for the Snowy River project with the interception of the reef at a depth of 880m below surface and was accessed via our southern decline (tunnel).”

By gaining access to the reef, staff could now take samples.

Federation said it would provide “important insights for our technical teams to confirm our geotechnical and extraction strategies as we progress closer to moving the project into a production phase.”

Greymouth Mayor Tania Gibson said the mine was a great benefit to the West Coast economy.

It came as other positive discussions were occurring in the mining sector, she said, referring to the upbeat remarks by Resources Minister Shane Jones during his visit to Greymouth last week.

Hitting the Birthday Reef was a major achievement and a big obstacle to overcome.

As the mine cranked up, there would be more downstream benefits for the economy, Mrs Gibson said.

“Investors are looking in many areas,” she said, noting improvements to the Greymouth central business district.

Federation expects the workforce to grow to 140 when it moves into gold production.

The old Blackwater Mine produced 21 tonnes of gold before the shaft collapsed.

Odt 21/2/2024


Thanks a lot for sharing!

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Bloody awesome.

JW :cowboy_hat_face:

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Excellent results hope they do well

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Shame it isn’t a kiwi company. So typically all the gold profit will go off sure all be 1% gold tax that the government gets. Ok, it will involve a bit of employment locally, but nowhere near what the gold could be worth to New Zealand. NZ getting sold short yet again. :roll_eyes:

Jw :cowboy_hat_face:


880m down! Thats a long way



The Birthday Reef was the most productive gold producer during historic mining of the Reefton goldfield on the west coast of the South Island of New Zealand. Deep exploration drill holes (up to 1.6 km long) intersected the mineralised quartz vein zone and adjacent hydrothermal alteration halo beneath the historic mine workings. The Paleozoic metasedimentary host rocks contain between 0.5 and 8 ppb Au and between 4 and 30 ppm As, and metamorphic pyrite typically contains 0.1 to 1 ppm Au in solid solution. The Au and As halo, above these background values, extends <20 m from the Birthday Reef, and other petrographic indicators of alteration are also confined to this narrow envelope. Porphyroblasts of pyrite and arsenopyrite, with minor Au enrichment, grew across the metamorphic cleavage in the alteration halo before emplacement of the Birthday Reef and associated shearing, and reflect an earlier, late metamorphic precursor to the main gold mineralisation phase.

Most orogenic gold deposits are dominated by metre-scale quartz veins that constitute a small target for explorationists. There is typically some alteration of the immediate wall rock to the veins, which can increase the width of the exploration target. However, the widths of these alteration zones vary as a result of the structural, lithological and geochemical processes involved in mineralisation. Hence, each individual deposit has its own characteristics, which hinders accurate prediction of the scale of exploration targets at the surface and in drill holes.

The Reefton goldfield of New Zealand (Figure 1) is a dismembered portion of the Lachlan Orogen of southeastern Australia, a well-endowed gold-bearing terrane with abundant orogenic vein deposits. Several attempts have been made to define the scale of wall rock alteration in Lachlan Orogen gold deposits, but because each deposit is unique, the characteristic footprint features defined in one deposit are rarely extendable to other deposits. Similarly, within the Reefton goldfield itself, there is a wide range of styles of mineralisation and resultant alteration footprints, which range from only centimetres to several tens of metres from veins
Historically one of the richest gold-producers in the Reefton goldfield, apparently has an extremely narrow zone of adjacent alteration (metre scale), and this alteration zone is the focus of this study. The Birthday Reef is essentially a single quartz vein, typically c. 0.6 m wide, with a steep dip that was the target for deep historic underground mining. Modern exploration activity has required deep drilling beneath the historic workings, and drill holes up to 1600 m long have been emplaced as part of the deepest gold-related drilling programme in New Zealand.
In this study, we used material from some of these deep drill holes to define the width of the alteration zone adjacent to the Birthday Reef and determine the hydrothermal features that constitute the footprint of the Birthday Reef mineralisation. We use low detection limit gold analyses to determine the extent of the gold enrichment halo in relation to background gold concentrations. We then integrate the gold halo with other geochemical and petrographic features of the alteration zone.

General geology

The Reefton goldfield lies on the western side of the South Island of New Zealand, and is hosted by Paleozoic metasediments of the Greenland Group in the Western Province.

These host rocks in the Reefton goldfield consist of turbiditic greywackes and argillites that have been metamorphosed to lower greenschist facies, preserving bedding and some sedimentological features.
A pervasive metamorphic cleavage cuts bedding at a range of angles associated with tight upright folding on the kilometre scale, with a north to northeast trend. Granitoid intrusives were emplaced into the Greenland Group in the late Paleozoic and Cretaceous. The Greenland Group in the Reefton goldfield was exhumed in the late Paleozoic, and is locally unconformably overlain by Devonian and early Cenozoic sediments. Gold mineralisation in the Reefton goldfield was controlled by faults that locally cut across, but are partially related to, the upright to steeply inclined fold hinges.

The Birthday Reef strikes north–northeast, sub-parallel to the fold axial surfaces of the hosting folds and the bedding that defines those folds. Known strike length is >1 km, and historic mining extended to >800 m below the surface. The historic mining extracted >700,000 ounces of gold (>22 tonnes), and typical gold grades were in excess of 15 g/tonne, before the mine closed in 1951. Recent exploration drilling has intersected the Birthday Reef a further 700 m below the last worked level of the mine, leading to an inferred resource estimate of c. 700,000 ounces of gold for this delineated portion of the reef.