Alvar Soesoo, in his presentation at the EU Supercluster Geoconference, delivered compelling insights into Estonia's abundant mineral resources, catering to the interests of geoscientists and mining engineers. Here are the 5 key points that emerged from his theses.
- Rich Metal Occurrences in Paleoproterozoic Rocks: Estonia's Paleoproterozoic crystalline basement harbors notable metal occurrences, particularly in the form of magnetite-gneisses enriched in manganese (Mn), boasting concentrations of up to 6 wt%. The Jõhvi crystalline rock complex in northeastern Estonia, among other locations, showcases these mineral-rich gneisses. Historical estimates suggest the presence of over 300 million tons of magnetite ore in this region.
- Phosphorus and Rare Earth Elements (REEs): Estonia possesses an extensive, largely untapped resource of sedimentary phosphate rock, estimated at around 3 billion metric tons. The geological formations responsible for these deposits contain brachiopod debris, which can exhibit P2O5 concentrations of up to 35–37 wt%. Historically, these phosphorite deposits have undergone extensive study, but political challenges, notably the "Phosphorite War" in the 1980s, interrupted further research for nearly two and a half decades. Recent geological-geochemical assessments, along with analysis of new drill cores, have shed light on the presence of enriched REEs, with varying concentrations for elements such as La, Ce, Pr, Nd, Sm, and Gd. While these deposits are not currently deemed economically viable for standalone REE extraction, they present potential value as co-products in the production of phosphate fertilizers, aligning with contemporary socio-political-technological developments. In the context of conventional mining operations, it is estimated that Estonia could yield up to 720 tons of REEs, 120 tons of uranium, and 27 tons of thorium annually.
- Kukersite Oil Shale: Kukersite oil shale has been a cornerstone of Estonia's energy industry for over a century. While it has been crucial for energy independence, a transition to more sustainable energy sources is necessary, with the potential for continued use in the chemical industry. Estonia's kukersite deposits are extensive, covering an area of approximately 3,000 square kilometers. The estimated total resource of kukersite in Estonia is about 4.63 billion tons. Kukersite has been a key energy resource in Estonia, with organic matter content ranging from 15% to 55%. It has been a source of energy independence for the nation, with a calorific value of up to 15 MJ/kg. While the direct use of Kukersite for energy generation may become impractical, its rich reserves offer the potential for future applications, particularly in the chemical industry, as Estonia transitions to cleaner and more sustainable energy sources.
- Graptolite Argillite: Estonian graptolite argillite is a type of black shale characterized by high concentrations of several metals, including uranium (U), molybdenum (Mo), vanadium (V), and nickel (Ni), along with other heavy metals. It has a sapropelic origin and formed over millions of years. During the Soviet era, graptolite argillite was mined in the vicinity of Sillamäe town in northeast Estonia for uranium production. Approximately 73 million tons of this rock were extracted and piled into waste heaps at Maardu phosphorite opencast pit, near Tallinn. The estimated resource of Estonian graptolite argillite is vast, with an estimated tonnage of 65–70 billion tons. However, due to the complex geological section where graptolite argillite overlies phosphorite ore, further mining of these resources presents challenges and complexities.
- Carbonate Rocks: Estonian carbonate rocks, mainly limestones and dolostones, have played a crucial role in the construction industry, both locally and through export to countries like Germany, Russia, Latvia, and the Nordic nations. These rocks have been used for building castles and medieval towns. In 2021, Estonia extracted dolostone from 37 mines, totaling 834 thousand cubic meters, primarily used as an aggregate in construction. Limestone was extracted from 61 mines, amounting to approximately 2,491 thousand cubic meters. These carbonate rocks continue to serve various local needs and are used in construction works. As of December 31, 2021, active dolostone reserves in Estonia were estimated at 100,940 thousand cubic meters. Active limestone resources in Estonia were estimated at 245,310 thousand cubic meters. These figures highlight the substantial reserves of carbonate rocks available for future use. Dolostone, a type of carbonate rock, has the potential application in metallic magnesium extraction, which could have broader industrial applications.
.JPG "Alvar Soesoo presenting his talk at the EU Supercluster Geoconference in Rovaniemi, Finland.")