A Hg-rich gold mineral association in the Migollas massive sulphide deposit from the Iberian Pyrite Belt, Spain

Within the "Cu-rich brechico" horizon at lower orebody of the Migollas deposit (IPB, Spain), remobilized ores generally contain the highest gold contents (up to 4 g/t). This horizon mainly consists of sulphides, carbonates, sulphosalts, native bismuth and occasional gold grains. The gold is present as Au-Ag-Hg-alloys, associated to polymetallic Cu-Zn-Pb-Bi-Sb-As assemblages within fractures in pyrite ores. This study evidences that metals of the cited alloys were remobilized from previously formed massive sulphides, and reconcentrated during the subsequent hydrothermal replacement process.