The Waihi vein system is hosted within andesitic flows and pyroclastic units of the late Miocene (7.36-6.76Ma) Waipupu Formation. The Waipupu Formation in Waihi can be subdivided into an upper quartzphenocryst poor unit and a lower quartz-phenocryst rich unit which dip shallowly towards the SE. Some of the veining and gold mineralisation in Waihi appears to be better developed within the lower quartz-rich andesite flows, with the exception of the Favona, Moonlight and GOP deposits which are solely hosted within the upper andesite unit. Much of the mineralised andesites in Waihi are overlain by post-mineral rocks including dacite flows of the Uretara Formation (5.23Ma), Pleistocene ignimbrites and recent ash deposits.

Where veining is exposed close to the surface, the quartz-adularia altered andesites form resistant paleotopo ‘highs’ that project through the post-mineral cover sequences.

Martha Vein System
The Martha Vein System is the largest and most documented of the vein networks in Waihi. The veins are numerous and form a large network that extends for more than 1600m along strike and 600m below the surface. The vein network although complex in detail, simply comprises the dominant southeast-dipping Martha vein and several northwest-dipping hangingwall splays including the Empire, Welcome, Royal and Rex veins. The Martha vein is the largest vein structure reaching up to 30m in thickness in places but averages 6 to 15m wide. Increased vein widths ........

Permits and consents have been granted for MUG project and all selected mining methods are in accordance with the license, permit and consent conditions, principally related to placement of backfill, blast vibration limits, method of working and hydrogeological controls. Exploration drives were completed on 800 m RL and 920 m RL in 2018. Development of MUG commenced in mid-2019 and 2,169 m of lateral development and a 120 m ventilation raise were completed by the end of 2019.

The Martha underground is accessed via the existing Favona portal through the existing Trio and Correnso workings and shares the ventilation development and shafts as well as the Correnso workshop, Trio cribroom and dewatering systems. Exploration drives were completed on 800 m RL and 920 m RL in 2018.

Development of Martha underground commenced in mid-2019 and 2,169 m of lateral development and a 120 m ventilation raise were completed by the end of 2019 and a further 7,554 m of lateral development completed in 2020. Two breakthrough openings into the pit for ventilation and escape were also completed. Development up to end 2020 has been focussed on ramp accesses for Edward, Empire, Rex and Royal mine zones, ventilation connections, pumping well access drives, drilling platforms and back fill drives as well as the breakthroughs into the pit.

Four mining methods are proposed for the mine:
1. Modified Avoca with rockfill in previously unmined areas.
2. Modified Av ........

- subscription is required.

- subscription is required.