Recent detailed diamond core logging carried out in conjunction with sampling for petrology has determined there to be a "pre-requisit" structural control to mainly lithostragraphically controlled gold mineralisation at the Neavesville low-sulphidation epithermal gold deposit, Coromandel, New Zealand. Diffuse zones of silica cemented strucally controlled hydrothermal brecciation cross-cut a gentely dipping sequence of silica flooded formerly permeable fine to course grained clastic rocks. High grade minealisation in relation to hydrothermal brecciation correlates with native gold/electrum contained within structurally constrained hydrothermal breccia cement. Some of the crosscutting hydrothermal breccias entrain fragments of magmatic hydrothermal/porphyry style vein material indicaing a porphyry system at depth.
Porphyry/magmatic hydrothermal style quartz vein fragment enclosed by silicic altered pyroclastic breccia or hydrothermal eruption breccia. 300 microns field of view, cpl.
Native gold/electrum (enclosing grains of pyrite) intergrown with mosaic quartz and pyrite of hydrothermal breccia cement. 300 microns field of view, ppl/rl.
Native gold/electrum intergrown with and interstitial to mosaic quartz and pyrite of hydrothermal breccia cement. 300 microns, ppl/rl. 70 microns field of view, ppl/rl