Critical Raw Materials (CRM) potential of Slovenian historical mining sites

Of the more than 200 metal ore occurrences and deposits discovered on Slovenian territory, several have been developed into significant mines (e.g. the Idrija Hg mine or the Mežica Pb-Zn-Mo mine). After 1995, however, all metal mines in Slovenia were closed, which also led to an interruption in mining exploration. The potential of the Slovenian ore deposits to supply Critical Raw Materials (CRM) remained largely unknown, as the historical mining exploration concentrated only on the most important base metal commodities, while the presence of trace elements was ignored. The GeoERA- FRAME project initiated a re-evaluation of the Slovenian ore deposits according to their CRM potential. Litija Pb-Zn-baryte hydrothermal vein deposit in central Slovenia, hosted by Carboniferous sandstones, may serve as a good case study for the evaluation of historical data with a focus on CRMs. The mine was active in the period 1537-1966 and produced about 30,000 t Pb, 32,000 t baryte, 158 t Hg and 2.8 t Ag (Mlakar, 1993). Litija was the largest baryte mine on Slovenian territory and still contains about 0.1 Mt ore resources with a baryte grade of 20%. In addition, the Pb and Zn mineralization in Litija may contain elevated levels of Ag, Sb, Co, Ga, Ge and In (Drovenik and Pleničar, 1980). Historical data indicate that approximately 0.5 Mt of mining waste was produced during mine operation with an estimated grade of 1.97% Pb and 0.48% Zn. In order to assess the potential of CRM, mining waste and accessible ore veins will be sampled and analyzed with modern multi-element chemical analyses. As parts of the mining waste deposits are populated or have been transported away, a re-assessment of the volume of accessible mining waste will be also carried out. New geochemical analyses shall be performed on samples from all ore deposits on Slovenian territory in order to identify potential mineral deposits of public importance and to define suitable spatial planning guidelines. Literature: Drovenik M. and Pleničar M. 1980. Nastanek rudišč v SR Sloveniji (The origin of Slovenian ore deposits). Geologija 23/1, 1-157. Mlakar, I. 1993. O problematiki Litijskega rudnega polja (On the problems of the Litija ore field). Geologija 36, 249-338. doi: 10.5474/geologija.1994.013