.
Location: 112 km SE from Auckland, New Zealand
43 Moresby AvenuePO Box 190 Waihi 3641WaihiNew Zealand3610
Stay on top of the latest gold discoveries. Examine the latest updates on drilling outcomes spanning various commodities.
Mining scale, mining and mill throughput capaciites.Full profiles of select mines and projects.
Shaft depth, mining scale, backfill type and mill throughput data.Full profiles of select mines and projects.
Equipment type, model, size and quantity.Full profiles of select mines and projects.
Camp size, mine location and contacts.Full profiles of select mines and projects.
- subscription is required.
Martha deposit is considered to be typical of epithermal vein gold-silver deposits.The gold and silver mineralization occurs within low-sulphidation, epithermal quartz vein systems occupying large, north to northeast trending, normal faults and their subsidiary extensional structures. The vein systems comprise a 3D network of multiple vein sets that collectively strike >1000 m, with a current vertical range of 300 m (Wharekirauponga) and >500 m (Waihi) and include veins typically between 0.5 and 5 m in width (but up to 30 m locally). The main gold bearing minerals are electrum and silver sulphides developed within quartz veins.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 1600 m along strike and 600 m below the surface. The vein network although complex in detail, simply comprises the dominant southeast-dipping Martha vein and several northwest-dipping hanging wall splays including the Empire, Welcome, Royal and Rex veins. The Martha vein is the largest vein structure reaching up to 30 m in thickness in places but averages 6-15 m wide. Increased vein widths are closely associated with the steepening of vein dips from an average of 65 to 70 degree to approximately 85 degree to the southeast. Steeper portions of the vein tend to contain higher concentrations of Au and Ag. The vein itself comprises mainly intact brecciated quartz vein material evidence for vein emplacement during the late stages of dip-slip faulting. The quartz is characterized by multiphase brecciation, and banding (colloform and crustiform) and quartz textures are highly variable from a fine, microcrystalline, and chalcedonic character to more coarsely crystalline particularly at depth. Apart from the main Martha vein, the hanging wall splay veins are also significant mineralized structures reaching 18 m width. The hanging wall splays closest to Martha link up with the Martha vein at depth often forming a higher-grade lode at the intersection. The hanging wall splays further away from Martha either thin out at depth or are not drilled deep enough to make out their relationship with Martha at depth. Additional, smaller-scale splay veins are present linking the larger vein structures and form a valuable contribution to the mineralization particularly in Martha Open Pit (MOP). These splays typically comprise smaller veins between 5 and 50 cm in width in filling extensional structures with no fault displacement, dipping mode rately towards the northwest. Two steeply dipping, NNE-trending and well mineralized vein structures and form an important part of the overall Martha vein network.Gold occurs mostly as small inclusions of electrum (averaging 38 % silver) occurring as both free grains in the quartz and as inclusions in sulphides such as pyrite, galena, sphalerite and less commonly chalcopyrite. Free gold is rarely observed. Acanthite associated with pyrite and galena is the main silver mineral. Martha ore has silver to gold ratios of > 10:1, The Favona and Trio ores had silver to gold ratios of ~ 4:1, and Correnso ore had a silver to gold ratio of less than 2:1.
