The discovery of the Borobia world-class stratiform magnesite deposit (Soria, Spain): a preliminary report
A new world-class stratiform magnesite deposit has been recently discovered near the village of Borobia in Soria, Spain. The mineralization consists of a 25–45 m massive to banded magnesite layer sandwiched in between a Lower Cambrian carbonate formation and an upper shale horizon. It forms an arcuate belt striking NW–SE to W–E, which outcrops for 7.3 km in two elevations separated by a central valley that is covered by a thin layer of Pleistocene sediments. The orebody is confined by two regionally important faults and is probably associated with the dolomitization and silicification of the Cambrian limestones. Geological ore resources are estimated to exceed 175 Mt with MgO contents varying from 36 to 47% by weight. At present, the owners, Magnesitas y Dolomías de Borobia, S.L., are at an advanced stage of planning for extraction. This report presents some results of an ongoing geological exploration programme and shows the general features of the geology and mineralogy of the Borobia deposit.