Distribution of precious metals in the Bleikvassli Zn-Pb Sedex type deposit, Nordland, Norway

Abstract

In contrast to the volcanic hosted massive sulfide deposits, the presence of recoverable gold is not a common feature of sedex type Pb-Zn deposits. However, the available data suggest that the gold content in the Bleikvassli deposit could be higher than previously assumed. This report comprise the results of field work on the Bleikvassli Pb-Zn deposit, Nordland, Norway. The main goals have been to study the distribution of precious metals in the massive ore in the wall rocks and furthermore to evaluate the mode of occurrence of precious metals. During the field season in 1995, 11 drillholes from profiles 360N, 520N and 700-740N were relogged and sampled in continuous intervals across the ore zone. Five short profiles were also sampled across the massive sulfide body in underground workings. Drill hole intersections, which showed gold and\/or silver enrichment during routine analysis by the mining company, were sampled for microscopic and microprobe studies. During the study of gold and silver rich intervals from the drill holes, it was clear that mobilizate type veinlets and disseminated sulfide mineralizations hosted by quartz +- feldpar veins, \"quartzite-like\" rocks and muscovite schist dominate in the precious metal rich intervals. Until now, 434 samples have been analyzed.