The past fourteenth of May, ten of our students went to a fieldtrip to Sant Julià de Llor i Bonmatí mining district. Located in the, Montseny-Guilleries region, this  district had a great importance in the Spanish mining history, and was active during eighteenth, nineteenth and twentieth centuries (until 1972).

 

The main objective of this fieldtrip was to study the “Puig de Sant Julià” open-pit mine, where F-Ba (Pb-Zn- Cu) mineralisations were extracted. These mineralisations are located in fracture-associated veins, strata-bounded layers and Cambrian to Silurian metasomatic marbles and calc-silicates (Skarns).

 

The minerals that form the host rocks are mainly carbonates, such as calcite and dolomite, but there is also quartz, tremolite-actinolite, diopside and white micas (phlogopite and/or margarite).

 

The minerals forming the ore deposits are mainly sulfides, such as pyrite, chalcopyrite and galena. Malachite, pyrolusite, melanterite and goethite are present, but as a product of sulfide alteration (supergene). Additionally, some barite veins are found cutting the host rock and ore deposits.