The Mosteiros orogenic lode gold prospect, east-central Portugal: a case study for the occurrence of invisible gold

摘要

The study of invisible gold, often refractory in nature, has gained prominence since the recent exploitation of relatively large tonnage, lower-grade gold deposits that can be mined by heap-leaching techniques. The Mosteiros gold prospect, hosted in meta-sedimentary rocks of the Serie Negra series, and occurring within the Tomar Cordoba shear zone, contains such refractory gold. The prospect is defined as a rectangular area (27 km~2) with interesting gold soil anomalies, but where trenching and drilling have revealed only low gold grades. The occurrence of native gold is scarce, but there is evidence for lattice-bound gold associated with pyrite and arsenopyrite. As a result of the presence of invisible gold, problems such as ore dressing techniques and gold recovery rates are additional factors that must be considered should ore extraction ever be considered.