The growing demand for critical raw materials (rare earth elements—REE, Nb, Ta, and others) enforces a need to look for their alternative sources. Distortions of the mineral supply chain caused by COVID-19 have necessitated a re-evaluation of what exists as mining waste from previous exploitation. Consequently, this study aims to provide an inventory of raw materials on the Indonesian Tin Islands (Bangka and Belitung). Geological and mineralogical examinations on Bangka have permitted an economic appraisal of tailings from the processing of cassiterite-bearing sands and confirmed the presence of REE-bearing minerals, chiefly monazite and xenotime, zircon, ilmenite, rutile, niobium-tantalum phases. In general, the mineral content of the tailings varies depending on the sampling site and the type of processing used during ore-production. ICP-MS (inductively coupled plasma–mass spectrometers) analyses revealed anomalous concentrations of LREE (light rare earth elements): La > 5%, Ce > 5%, Pr > 1%, Nd > 1%, Sm > 1% and HREE+Y (heavy rare earth elements and yttrium) up to 2.51 wt%. High values have been found for the “most critical” metals of the HREE group: Dy (up to 0.34 wt%), Tb (up to 0.08 wt%), Eu (up to 61.8 ppm), Nd (>1.0 wt%), and Y (up to 1.20 wt%). In addition, the following contents have been defined: Ga (to 0.03 wt%); Hf (to 0.64 wt%); Ta (to 0.08 wt%); Nb (to 0.23 wt%); W (to 0.14 wt%); Zr (>5.0 wt%); and Sc (to 0.01 wt%). Such high concentrations suggest the tailing dumps to be a potential new source of “critical raw materials”.

The European Commission has adopted the European Green Deal strategy, which aims to achieve climate neutrality in the EU by 2050. To achieve this goal, it is necessary to shift the economy toward the use of green and renewable energy. Critical raw materials (CRMs), Li, Co, REE, Te, Sc and others, are used in renewable energy sources (RES) production. The EU lacks its own CRM deposits, and additionally, the access to already identified deposits is limited, which is making the EU countries search for alternative CRM sources. One such source of CRMs may be mining waste generated on the Indonesian island of Bangka as a result of processing cassiterite-bearing sands. Studies of the mineral composition of the waste using the XRD method reveal rich contents of xenotime (0.79–17.55 wt%), monazite (1.55–21.23 wt%), zircon (1.87–64.35 wt%) and other minerals, carriers of valuable metals, such as Sn, Ti, Nb, Ta. The point mineral chemistry analyses were performed using EPMA. Xenotime is the main carrier of heavy rare earth elements (HREE), especially the “most critical” HREEs: Gd₂O₃ (1.42–7.16 wt%), Dy₂O₃ (2.28–11.21 wt%), Er₂O₃ (2.44–7.85 wt%), and Yb₂O₃ (1.71–7.10 wt%). Xenotime is characterized by a complex internal structure resulting from metasomatic processes occurring during their formation. In SEM-BSE imaging, they show zonation of internal structure, which is the effect of an HREE, Y, Si and U substitution in the crystal structure. On the other hand, thorite ThSiO₄ and uranothorite (Th,U)SiO₄ inclusions are present in xenotimes. The ICP-MS/ES studies of tailings reveal very high contents of HREE + Y (up to 7.58 wt%), U (up to 0.11), Th (up to 0.75 wt%) and Sc (132 ppm). A CRM source diversification is part of the strategy to ensure the security of raw materials for countries of the European Union and the green transformation of the continent. Bilateral EU–Indonesia cooperation in the geological exploration and development of primary and secondary sources may contribute to an increase in the supply of HREEs to the global market.

Between 1976–1990, the Polish Geological Institute performed geological works in the Polish Maritime Areas. During these works, 260 occurrences of concretions were recorded from 7,500 sampled sites. In 1980, the threshold that separates the Bornholm Basin from the Słupsk Furrow was mapped. Numerous Fe-Mn nodules on the seabed were found in that area. The results of detailed analyses of nodule samples collected from four sites are presented in this paper. Analyzed nodules represent discoidal D, irregular I, and transitional D-I types. The nodules are characterized by varied chemical composition of main oxides (Fe, Mn). The maximum Fe2O3 content is 26.63% and MnO 23.18%. Total average amount of REE + Y in the samples is approximately 165.11 ppm, ΣLREE 145.72 ppm and ΣHREE 19.39 ppm. The LREE content is enriched in comparison to HREE. The majority of nodules consist of Fe-Mn oxy-hydroxide minerals with very low crystallinity (practically amorphous phases). The main confirmed Mn-phases are birnessite and todorokite. Other main components of the nodules are: detrital quartz, albite, microcline, glauconite and muscovite, clinochlore, and clay minerals: illite and chlorite. The rate of growth of Fe-Mn nodules has been estimated using a cobalt chronometer. The nodule growth rate ranges from 0.006 to 0.134 mm/yr –1. Based on the Fe, Mn and (Cu + Co + Ni) contents, the origin of studied nodules is determined as hydrogenetic, while using REE (Cesn/Cesn · vs. Nd) – as diagenetic.

Eastern Indonesia, including the island of Halmahera, is a region with a high mineral potential, particularly Ni-Co, Au-Cu, and Ag ores, which are a globally important and critical source of raw materials (CRMs). The research was conducted within the framework of scientific cooperation between the Faculty of Geology, University of Warsaw (Poland), and PT Halmahera Resources Percasa Ltd. (Jakarta, Indonesia) Between the years of 2009 and 2011, 42 boreholes were drilled using an impact system (up to 15 m below surface) and 3 test pits (up to 8 m below surface). The presence of a laterite deposit containing Ni-Co mineralization was identified on the license area. The resources estimated in accordance with JORC Code, with a cut-off grade Ni ≥ 0.5%, equaling 185,510 t Ni and 17,747 t Co, with the stock of raw material amounting to 14.8 million t and with an average content of 1.00% Ni and 0.13% Co. The ore in the deposit has mixed character. To date, studies have shown the dominance of oxide ore, but saprolite composed of magnesium silicates was also identified in significant amount. The Ni mineralization in oxide ore (limonite) is bound to goethite and manganese minerals, while in the case of silicate (saprolite) ore, it occurs locally in the form of veins as well as zonally in the weathered serpentinites. Cobalt mineralization is almost entirely related to the Mn minerals that occur in the lower oxide zone. It has been found that both serpentinites and harzburgites (and possibly locally lherzolite) are the parent rocks for laterite deposit.

Indicator minerals (IM) have been used in the research of gemstone and base metals for over 100 years. IMs are a main source of information about the occurrence of deposits, hydrothermal and weathering changes, as well as bedrock source and type. Since 2013, base metal mineral exploration has taken place on New Guinea Island (the Indonesian part). The analysis of chromian spinels as IM in beach and river sediments led to the discovery of rich chromian-bearing deposits in the Botawa River sediments. The dominant detrital minerals include chromian spinels, olivine, pyroxenes and serpentine. The source of chromian spinels, olivine and pyroxenes are most likely peridotites from the Earth’s mantle zone of the ophiolite series, generated under supra-subduction conditions. The terrigenous deposits contain metamorphic minerals, such as staurolites, andalusites, epidotes, amphiboles and fragments of micas, quartz and chlorite schists. Using ICP-MS analysis of the beach sands, the concentration of Cr₂O₃ was determined to be at the level of 1.17%, while in the heavy minerals concentrate from the Botawa River sediment, the content of Cr₂O₃ amounts to 24.83%. The authors conclude that the west parts of the Van Rees Mountains are the probable parent rocks for chromium-bearing sediments.