The Hauraki Goldfield, west of Auckland, New Zealand, has some 50 epithermal quartz vein gold deposits that collectively have produced more than 10 Moz Au and 50 Moz Ag. The quartz veins vary dramatically in terms of size, texture, mineralogy and metal endowment. Vein size is an important feature in epithermal gold exploration, but large vein size does not necessarily equate with gold endowment, eg the 4 km long Tokatea Reef (Coromandel) and 4.5 km long Big Buck Reef (Waiorongomai) have low gold concentrations. Vein textures and mineralogy give clues to mineral deposition processes, such as boiling (i.e. lattice textures, adularia), that can be highly conducive for gold precipitation. It follows that detailed description and analysis of vein mineralogy and textures, and their spatial changes, will be useful in determining vein prospectivity, paleodepth and vectors to, and proximity of mineralisation.
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