**8. Czechoslovak uranium mining after World War II**

In 1945, the Soviet Union controlled all uranium resources in the Czechoslovakia and in the Soviet occupation zone in the Germany and later also in Poland. In East Germany and in Poland, the so-called stock companies for exploration and exploitation of uranium ore deposits were established in which the Soviet share represented fifty percent. In East Germany, the income from the uranium exploitation came on the account of war reparation up to 1953. In Czechoslovakia, talks between Czechoslovak Prime Minister Zdeněk Fierlinger and the Soviet diplomatic agent Ivan Bakulin about the uranium ore mining and exclusive export to Soviet Union from August 1945 were finished on 23 November 1945 when the "Memorandum of understanding between the governments of Soviet Union and Czechoslovakia about the extension of exploitation of radium-bearing uranium and concentrates in Czechoslovakia and their delivery to the Soviet Union" was signed. The Memorandum contained also an attachment, which proclaimed this document to be highly confidential. According to the Memorandum, the Joachim Mines State Enterprise was founded. Leading posts in this enterprise were taken over by the Soviet experts. The Memorandum, however, did not specify the costs of exported uranium ores. This problem was progressively discussed between 1949 and 1952 [28]. In 1945, the Jáchymov ore deposit represented the only available uranium source on the territory of the Soviet block where uranium ores could be exploited immediately. In East Germany, the first exploitation of uranium ores started in 1947 and 1948.

Today, the community of Bad Schlema is an amalgamation of the formerly separate communities of Niederschlema and Oberschlema. After rich radon springs were opened in the Marx-Semler gallery in Oberschlema between 1908 and 1912, the world's richest radium spa developed after 1918. Ten years later, it was counted among Germany's most important spas. Once the uranium mining was taken over by the Soviet occupation forces, the spa and the downtown of Oberschlema were utterly obliterated. After uranium mining came to an end in 1990, the mayor, Konrad Barth, organised Schema's revival as a spa town, which was realised in 1998 when the new "Spa house" (Kurhaus) was opened. The newly opened radon springs afforded ample bathing. In 2005, Saxony's state government bestowed upon the community official designation "Bad", after it had already been recognised as a radon

6 Uranium - Safety, Resources, Separation and Thermodynamic Calculation

**7. Uranium as fuel in the nuclear weapons and in the nuclear power** 

**8. Czechoslovak uranium mining after World War II**

Otto Hahn and Fritz Strassmann conducted the experiments leading to the discovery of uranium's ability to fission and release binding energy in 1934. Lise Meitner and Otto Robert Frisch published the physical explanation in February 1939 and named the process "nuclear fission". Further work found that U238 isotope could be transmuted into plutonium, which like U235 isotope is also fissile by thermal neutrons. These discoveries led to the United States, Great Britain and Soviet Union to begin work on the development of nuclear weapons and nuclear power. After World War II, following the Cold War between the Soviet Union and the United States, huge stockpiles of uranium were amassed and tens of thousands of nuclear weapons were created using enriched uranium and plutonium made from uranium ores. Uranium ore was, after 1949, a highly strategic mineral material. In Central Europe, the principal uranium ore deposits were discovered in the Czechoslovakia and the East Germany (GDR). Some small uranium ore deposits were also found in Poland. The uranium ore from these deposits was in the first place used for the Soviets' nuclear weapons, later also for nuclear power industry

In 1945, the Soviet Union controlled all uranium resources in the Czechoslovakia and in the Soviet occupation zone in the Germany and later also in Poland. In East Germany and in Poland, the so-called stock companies for exploration and exploitation of uranium ore deposits were established in which the Soviet share represented fifty percent. In East Germany, the income from the uranium exploitation came on the account of war reparation up to 1953. In Czechoslovakia, talks between Czechoslovak Prime Minister Zdeněk Fierlinger and the Soviet diplomatic agent Ivan Bakulin about the uranium ore mining and exclusive export to Soviet Union from August 1945 were finished on 23 November 1945 when the "Memorandum of understanding between the governments of Soviet Union and Czechoslovakia about the

spa since 2004 [18, 25].

**industry**

[9, 26–29].

From 1945 to 1949, in the Jáchymov uranium mines, the German war prisoners started to work, who were later replaced mainly by political and other Czechoslovak prisoners. The Jáchymov together with Horní Slavkov and Příbram became known as parts of the "Czech Gulag". In Jáchymov, 65,000 prisoners worked in concentration camps until 1961 [9]. For following exploration of uranium deposits on the Czechoslovak territory, in 1946, "Prospective geology group", which later evolved into the independent organisation, was established. Thirty Soviet geologists formed the nucleus of this group, and according to territorial responsibilities, the group was subdivided into seven subgroups. During 1948 and 1962, the Horní Slavkov uranium deposit was opened and exploited. In the Czech part of the Ore Mts. (Krušné Hory/Erzgebirge), some smaller ore occurrences and deposits (e.g., Potůčky, Abertamy) were exploited.

In the first stage of uranium exploration, the selected territories according to older geological studies and geological mapping were covered in 1958–1964 by emanometry, sampling from a depth of 1 m. Productivity of three-personnel groups was about 300–500 holes per day. Productivity of later used technique with 3 m holes was much lower, and with this technique, only limited areas were covered. Some other geophysical methods that were used for exploration of uranium deposits were ground and car-borne gamma-ray survey [30]. From 1946 to 1955, exploration for uranium ores was concentrated on the known vein deposits in the Ore Mts. area (Jáchymov and Horní Slavkov) and area of the known base-metal vein deposit Příbram. During systematic emanometry and gamma-ray surveys, a new type of hydrothermal uranium deposits evolved in mineralised shear zones (Rožná, Olší, Okrouhlá Radouň, Zadní Chodov and Vítkov II). The sandstone-hosted deposits in northern Bohemia (Hamr, Stráž, Břevniště, Osečná-Kotel and Hvězdov uranium deposits) were found after gamma logging of hydrogeological borehole [30]. In 1989, the decision was made to reduce all uraniumrelated activities. Following this decision, in 1990, expenditures decreased to about 7 million USD and have declined ever since. No field exploration has been carried out since the beginning of 1994 [31].

Most of the known uranium resources in the Czech part of the Bohemian Massif occurred in 32 ore deposits, of which 30 have been mined out or closed up to year 1993. Of two remaining deposits, the Rožná and Stráž were mined also from 1993 up to 1996 (Stráž) or up to 2017 (Rožná). The mining of the last Central European uranium deposit (Rožná) was stopped in April 2017. The very small recent production of uranium in the Stráž uranium deposit is part of remediation of the after-effects of the in-situ leaching that impacted a total 266 million m3

groundwater and an enclosure of 650 ha surface area. In former Czechoslovakia, a total uranium production from 1945 to 2017 was 112,250 t U. However, majority of uranium ore was mined in the Czech Republic. In Slovakia, in this time, only 211.4 t U was mined. In the Czech Republic from 2004, no prospection activities on uranium ore deposits exist. Recently, only different environmental remediation projects exist. The biggest project in area of the Stráž uranium deposit is expected to continue until approximately 2040 [31].

The mined uranium deposits in the Czech Republic could be divided into the three main genetic types: vein deposits, shear-zone deposits and sedimentary deposits (**Table 1**). The production of the 12 main uranium deposits is listed in **Table 2**. The Příbram, Jáchymov and Horní Slavkov uranium deposits represent the vein deposits. The Rožná, Zadní Chodov, Vítkov II, Olší, Okrouhlá Radouň and Dyleň deposits represent the shear-zone uranium deposits. The sedimentary deposits are evolved mainly in the Upper Cretaceous Uranium Ore District (Stráž, Hamr and Břevniště) (**Figure 1**). Only some small uranium deposits and occurrences were evolved also in the Carboniferous-Permian and Tertiary continental coalbearing sediments.

The Příbram uranium ore district extends along the northwestern contact of the Central Bohemian Plutonic complex (CBPC) with Neoproterozoic and Cambrian rocks of the Teplá-Barrandian Zone. The 3200 km<sup>2</sup> complex crops out between two contrasting crustal units, in the Teplá-Barrandian Zone to the NW and Moldanubian Zone to the SE, in the central part of the Bohemian Massif. The plutonic complex is made up of multiple individual plutons and smaller magmatic bodies that vary in age, petrographic and geochemical characteristics, shape, size, internal fabrics and relationships to the host rock structures, from older calcalkaline to potassium-rich calc-alkaline and ultrapotassic magmas. In the NW margin of the CBPC, in area of the Příbram ore district crop out biotite and biotite-amphibole granodiorites of the Blatná suite, together with the Marginal, high-K calc-alkaline biotite granites. The Neoproterozoic, a slightly metamorphosed flysch sequence, up to 2000 m thick, is overlain by a Lower Cambrian sediments, containing thin layers of quartz-pebble conglomerate at its base and slates at a higher stratigraphic position. A volcano-sedimentary complex underlies the Neoproterozoic flysch sequence, comprising intercalated claystones, sillstones and conglomerates. Both the Lower Cambrian and Neoproterozoic rocks are contact metamorphosed by the CBPC within an aureole that extends 1000 to 1200 m from the intrusive contact. This

aureole is also cut by aplite and lamprophyre dykes. The Neoproterozoic host rocks form a simple fold, the Příbram anticline, with NE-trending axis, roughly parallel to the CBPC contact. Brittle structures in the Příbram ore district may be classified relative to the axial plane of the Příbram anticline as: (i) the most prominent, longitudinal NE-striking faults, i.e. subparallel to boundary of Neoproterozoic metasediments with the CBPC, (ii) transverse NW-striking faults, and (iii) oblique, E- or N-striking faults. Ore veins in the ore district strike NW (44% of veins), N (43% veins), and NE (13% veins). The ore veins are from a few metres to several kilometres long, from a few centimetres to more than 10 metres wide and comprise three mineral assemblages (from older to younger): (1) sulphidic with Pb, Zn and Cu-Fe sulphides, (2) uraninite bearing and (3) sulphide-selenide-carbonate. The main U-bearing minerals are uraninite and U-anthraxolite, coffinite being far less abundant. Uranium minerals occurred as veinlets, coatings and pods in calcite gangues. The deposit has been mined to a depth exceed-

**Uranium deposit Mining Production, t U**

History of Uranium Mining in Central Europe http://dx.doi.org/10.5772/intechopen.71962 9

Příbram 1950–1991 50200.8 Rožná 1657–2017 22220.0 Stráž 1967–1996 14674.1 Hamr 1972–1993 13263.8 Jáchymov 1946–1964 7950.0 Zadní Chodov 1952–1992 4150.7 Vítkov II 1961–1990 3972.6 Olší 1959–1989 2922.2 Horní Slavkov 1948–1962 2668.3 Okrouhlá Radouň 1972–1990 1339.5 Břevniště 1982–1990 1107.8 Dyleň 1965–1991 1100.5

**Table 2.** Production of uranium in the main uranium deposits of the Bohemian Massif [32].

The Rožná and Olší uranium deposits occur in the uppermost Gföhl unit of the high-grade metasediment series of the Moldanubian Zone. The host rocks of the Rožná U deposit consist predominantly of biotite paragneisses with intercalations of amphibole-biotite gneisses, amphibolites and small bodies of calc-silicate rock, marble, serpentinite and pyroxenite. The disseminated uranium mineralisation is coupled in the longitudinal N-S to NNW-SSE ductile shear zones, dipping WSW at an angle of 70–90°. The main mineralised shear zones of the Rožná uranium deposit are designated as the Rožná 1 (R1) and Rožná 4 (R4). In the less strongly mineralised Rožná 2 (R2) and Rožná 3 (R3) shear zones, numerous carbonate veins occur. Mineralised shear zones are segmented by steep, ductile to brittle NW-SE and SW-NE

ing 1500 m and total mined amount of U was 50200.8 t [32].

striking faults with younger carbonate-quartz-sulphide mineralisation.


**Table 1.** Genetic types of uranium deposits in the Bohemian Massif [32].


**Table 2.** Production of uranium in the main uranium deposits of the Bohemian Massif [32].

groundwater and an enclosure of 650 ha surface area. In former Czechoslovakia, a total uranium production from 1945 to 2017 was 112,250 t U. However, majority of uranium ore was mined in the Czech Republic. In Slovakia, in this time, only 211.4 t U was mined. In the Czech Republic from 2004, no prospection activities on uranium ore deposits exist. Recently, only different environmental remediation projects exist. The biggest project in area of the Stráž

The mined uranium deposits in the Czech Republic could be divided into the three main genetic types: vein deposits, shear-zone deposits and sedimentary deposits (**Table 1**). The production of the 12 main uranium deposits is listed in **Table 2**. The Příbram, Jáchymov and Horní Slavkov uranium deposits represent the vein deposits. The Rožná, Zadní Chodov, Vítkov II, Olší, Okrouhlá Radouň and Dyleň deposits represent the shear-zone uranium deposits. The sedimentary deposits are evolved mainly in the Upper Cretaceous Uranium Ore District (Stráž, Hamr and Břevniště) (**Figure 1**). Only some small uranium deposits and occurrences were evolved also in the Carboniferous-Permian and Tertiary continental coal-

The Příbram uranium ore district extends along the northwestern contact of the Central Bohemian Plutonic complex (CBPC) with Neoproterozoic and Cambrian rocks of the Teplá-

the Teplá-Barrandian Zone to the NW and Moldanubian Zone to the SE, in the central part of the Bohemian Massif. The plutonic complex is made up of multiple individual plutons and smaller magmatic bodies that vary in age, petrographic and geochemical characteristics, shape, size, internal fabrics and relationships to the host rock structures, from older calcalkaline to potassium-rich calc-alkaline and ultrapotassic magmas. In the NW margin of the CBPC, in area of the Příbram ore district crop out biotite and biotite-amphibole granodiorites of the Blatná suite, together with the Marginal, high-K calc-alkaline biotite granites. The Neoproterozoic, a slightly metamorphosed flysch sequence, up to 2000 m thick, is overlain by a Lower Cambrian sediments, containing thin layers of quartz-pebble conglomerate at its base and slates at a higher stratigraphic position. A volcano-sedimentary complex underlies the Neoproterozoic flysch sequence, comprising intercalated claystones, sillstones and conglomerates. Both the Lower Cambrian and Neoproterozoic rocks are contact metamorphosed by the CBPC within an aureole that extends 1000 to 1200 m from the intrusive contact. This

complex crops out between two contrasting crustal units, in

uranium deposit is expected to continue until approximately 2040 [31].

8 Uranium - Safety, Resources, Separation and Thermodynamic Calculation

**Genetic type of deposit Production, t U**

Vein and shear-zone deposits 82,128 Cretaceous sandstones 29,014 Carboniferous-Permian sediments 608 Tertiary sediments 289 **Total 112,039**

**Table 1.** Genetic types of uranium deposits in the Bohemian Massif [32].

bearing sediments.

Barrandian Zone. The 3200 km<sup>2</sup>

aureole is also cut by aplite and lamprophyre dykes. The Neoproterozoic host rocks form a simple fold, the Příbram anticline, with NE-trending axis, roughly parallel to the CBPC contact. Brittle structures in the Příbram ore district may be classified relative to the axial plane of the Příbram anticline as: (i) the most prominent, longitudinal NE-striking faults, i.e. subparallel to boundary of Neoproterozoic metasediments with the CBPC, (ii) transverse NW-striking faults, and (iii) oblique, E- or N-striking faults. Ore veins in the ore district strike NW (44% of veins), N (43% veins), and NE (13% veins). The ore veins are from a few metres to several kilometres long, from a few centimetres to more than 10 metres wide and comprise three mineral assemblages (from older to younger): (1) sulphidic with Pb, Zn and Cu-Fe sulphides, (2) uraninite bearing and (3) sulphide-selenide-carbonate. The main U-bearing minerals are uraninite and U-anthraxolite, coffinite being far less abundant. Uranium minerals occurred as veinlets, coatings and pods in calcite gangues. The deposit has been mined to a depth exceeding 1500 m and total mined amount of U was 50200.8 t [32].

The Rožná and Olší uranium deposits occur in the uppermost Gföhl unit of the high-grade metasediment series of the Moldanubian Zone. The host rocks of the Rožná U deposit consist predominantly of biotite paragneisses with intercalations of amphibole-biotite gneisses, amphibolites and small bodies of calc-silicate rock, marble, serpentinite and pyroxenite. The disseminated uranium mineralisation is coupled in the longitudinal N-S to NNW-SSE ductile shear zones, dipping WSW at an angle of 70–90°. The main mineralised shear zones of the Rožná uranium deposit are designated as the Rožná 1 (R1) and Rožná 4 (R4). In the less strongly mineralised Rožná 2 (R2) and Rožná 3 (R3) shear zones, numerous carbonate veins occur. Mineralised shear zones are segmented by steep, ductile to brittle NW-SE and SW-NE striking faults with younger carbonate-quartz-sulphide mineralisation.

The North Bohemian Cretaceous uranium ore district (Stráž, Hamr, Břevniště ore deposits) is developed in the two Cenomanian formations, lower freshwater continental and upper marine sediments. The basement of the Upper Cretaceous sediments is formed in this area by low-grade metamorphic rock series (phyllites and quartzites) and small bodies of the Upper Proterozoic and Upper Devonian granitoids. The lower continental sediments are developed in the paleo relief depressions and are formed by conglomerates and pebbly to silty sandstones. All these sediments are usually enriched in organic matter. The sandstones of marine Cenomanian cover the whole area of uranium ore district. Its basal parts are formed by washout sediments, which are represented by silty sandstones. They are overlain by the sequence of Upper Cenomanian weakly cemented sandstones. Uranium mineralisation is developed in the basal part of the Cenomanian formation, and it is usually divided into four ore levels: A (freshwater sediments – stream and lacustrine sandstones), main B level is evolved at the base of marine Cenomanian in wash-out sediments; ore levels C and D are less extended and occur in the friable sandstones (C) and in the uppermost Cenomanian – fucoidal sandstone horizon (D). The mostly horizontal plates and lenses usually form the ore bodies. The thickness of these plates and bodies varies from decimetres to several metres. The mineralogical and geochemical composition of uranium mineralisation occurring in the North Bohemian

History of Uranium Mining in Central Europe http://dx.doi.org/10.5772/intechopen.71962 11

Uraninite, complex U-containing gels, hydrozircon, baddeleyite and U-Th-Ca phosphates (ningyoite and brockite) are main carriers of uranium. For these uranium-enriched minerals (uraninite, hydrozircon, ningyoite and brockite) is highly significant enrichment in rare earth elements (REE) and Y. Uranium mineralisation is also coupled with occurrence of REE or Y

In 2012, in preparation of the new State Energy Concept of the Czech Republic, technical and economic re-evaluation of remaining uranium resources was undertaken. Total identified conventional resources in 2013 amounted to 119,256 t U. These resources are located in the North Bohemian Cretaceous basin (the Stráž, Hamr, Osečná-Kotel and Břevniště deposits). However, all these resources remain strictly protected due to environmental concerns

In Slovakia, from 1954 to 1990, small uranium deposit in the Slovak Ore Mts. (Novoveská Huta) was mined. The uranium ores were mined as by-product of copper mining. The uranium mineralisation in the Novoveská Huta ore deposit (Gemericum) occurs in two horizons of Permian volcano-sedimentary formation. The upper horizon is a part of volcano-sedimentary complex of volcanoclastic sandstones and conglomerates overlying rhyolites and their tuffs. Ore bodies form lenses mostly concordant to wall rocks. Their thickness reaches several metres. Uranium mineralisation is concentrated, however, largely in matrix of volcanoclastic rocks. The lower ore-bearing horizon occurs in breccias of the upper part of volcano-sedimentary complex with intermediate volcanic rocks. The length of the mineralised horizon is 4 km, the width varies from 200 to 600 m and the thickness reaches up to 80 m. Lenticular ore bodies are thick from several metres to tens of metres. Uranium mineralisation is disseminated or forms veinlets. Uraninite and molybdenite are dominant in uranium ore of both main horizons. U-Ti oxides, pyrite, chalcopyrite, tennantite, galena, sphalerite and arsenopyrite accompany them.

Cretaceous uranium district is diversiform and unique [33–35].

(groundwater source protection zone) [31].

minerals (crandallite, chernovite-(Y), rhabdophane and synchysite) [35, 36].

**Figure 1.** Main uranium deposits in the Czech part of the Bohemian Massif.

Ore mineralisation in the Rožná and Olší uranium deposits is formed by (i) disseminated coffinite > uraninite > U-Zr-silicate mineralisation evolved in chloritised, pyritised, carbonatised, and graphitised organic matter-enriched cataclastites of ductile shear zones, (ii) uraninite > coffinite mineralisation in carbonate veins, (iii) disseminated coffinite > uraninite in albitised and hematitised rock series (aceites) along ductile shear zones and (iv) mostly coffinite ore bound on the intersections of the ductile shear zones with younger NW-SE and SW-NE faults. Ore lenses of disseminated ore in fault zones R1 and R4 are 3.5 m thick on average, ore grade is around 0.5% U, up to 10% U locally. Ore bodies in ore zones R2 and R3 host a large number of carbonate veins up to 2 m thick with U-mineralisation of the average grade 0.6% U. Ore bodies in aceites with predominance of coffinite on uraninite and U-Zr silicate have U-mineralisation of a grade 0.1–0.15% U, exceptionally 0.3% U. Disseminated U-mineralisation bound to oblique fault zones is usually hosted by quartz-carbonate-sulphide breccias at intersections with diagonal and longitudinal structures. Compared to other types of mineralisation, the ore bodies are small but contain relatively high-grade ore of average grade 0.8% U and up to 20% U in some ore shoots. Total mine production of the Rožná-Olší ore district was 25,142 t U with an average grade of 0.24% U [32].

The North Bohemian Cretaceous uranium ore district (Stráž, Hamr, Břevniště ore deposits) is developed in the two Cenomanian formations, lower freshwater continental and upper marine sediments. The basement of the Upper Cretaceous sediments is formed in this area by low-grade metamorphic rock series (phyllites and quartzites) and small bodies of the Upper Proterozoic and Upper Devonian granitoids. The lower continental sediments are developed in the paleo relief depressions and are formed by conglomerates and pebbly to silty sandstones. All these sediments are usually enriched in organic matter. The sandstones of marine Cenomanian cover the whole area of uranium ore district. Its basal parts are formed by washout sediments, which are represented by silty sandstones. They are overlain by the sequence of Upper Cenomanian weakly cemented sandstones. Uranium mineralisation is developed in the basal part of the Cenomanian formation, and it is usually divided into four ore levels: A (freshwater sediments – stream and lacustrine sandstones), main B level is evolved at the base of marine Cenomanian in wash-out sediments; ore levels C and D are less extended and occur in the friable sandstones (C) and in the uppermost Cenomanian – fucoidal sandstone horizon (D). The mostly horizontal plates and lenses usually form the ore bodies. The thickness of these plates and bodies varies from decimetres to several metres. The mineralogical and geochemical composition of uranium mineralisation occurring in the North Bohemian Cretaceous uranium district is diversiform and unique [33–35].

Uraninite, complex U-containing gels, hydrozircon, baddeleyite and U-Th-Ca phosphates (ningyoite and brockite) are main carriers of uranium. For these uranium-enriched minerals (uraninite, hydrozircon, ningyoite and brockite) is highly significant enrichment in rare earth elements (REE) and Y. Uranium mineralisation is also coupled with occurrence of REE or Y minerals (crandallite, chernovite-(Y), rhabdophane and synchysite) [35, 36].

In 2012, in preparation of the new State Energy Concept of the Czech Republic, technical and economic re-evaluation of remaining uranium resources was undertaken. Total identified conventional resources in 2013 amounted to 119,256 t U. These resources are located in the North Bohemian Cretaceous basin (the Stráž, Hamr, Osečná-Kotel and Břevniště deposits). However, all these resources remain strictly protected due to environmental concerns (groundwater source protection zone) [31].

Ore mineralisation in the Rožná and Olší uranium deposits is formed by (i) disseminated coffinite > uraninite > U-Zr-silicate mineralisation evolved in chloritised, pyritised, carbonatised, and graphitised organic matter-enriched cataclastites of ductile shear zones, (ii) uraninite > coffinite mineralisation in carbonate veins, (iii) disseminated coffinite > uraninite in albitised and hematitised rock series (aceites) along ductile shear zones and (iv) mostly coffinite ore bound on the intersections of the ductile shear zones with younger NW-SE and SW-NE faults. Ore lenses of disseminated ore in fault zones R1 and R4 are 3.5 m thick on average, ore grade is around 0.5% U, up to 10% U locally. Ore bodies in ore zones R2 and R3 host a large number of carbonate veins up to 2 m thick with U-mineralisation of the average grade 0.6% U. Ore bodies in aceites with predominance of coffinite on uraninite and U-Zr silicate have U-mineralisation of a grade 0.1–0.15% U, exceptionally 0.3% U. Disseminated U-mineralisation bound to oblique fault zones is usually hosted by quartz-carbonate-sulphide breccias at intersections with diagonal and longitudinal structures. Compared to other types of mineralisation, the ore bodies are small but contain relatively high-grade ore of average grade 0.8% U and up to 20% U in some ore shoots. Total mine production of the Rožná-Olší

ore district was 25,142 t U with an average grade of 0.24% U [32].

**Figure 1.** Main uranium deposits in the Czech part of the Bohemian Massif.

10 Uranium - Safety, Resources, Separation and Thermodynamic Calculation

In Slovakia, from 1954 to 1990, small uranium deposit in the Slovak Ore Mts. (Novoveská Huta) was mined. The uranium ores were mined as by-product of copper mining. The uranium mineralisation in the Novoveská Huta ore deposit (Gemericum) occurs in two horizons of Permian volcano-sedimentary formation. The upper horizon is a part of volcano-sedimentary complex of volcanoclastic sandstones and conglomerates overlying rhyolites and their tuffs. Ore bodies form lenses mostly concordant to wall rocks. Their thickness reaches several metres. Uranium mineralisation is concentrated, however, largely in matrix of volcanoclastic rocks. The lower ore-bearing horizon occurs in breccias of the upper part of volcano-sedimentary complex with intermediate volcanic rocks. The length of the mineralised horizon is 4 km, the width varies from 200 to 600 m and the thickness reaches up to 80 m. Lenticular ore bodies are thick from several metres to tens of metres. Uranium mineralisation is disseminated or forms veinlets. Uraninite and molybdenite are dominant in uranium ore of both main horizons. U-Ti oxides, pyrite, chalcopyrite, tennantite, galena, sphalerite and arsenopyrite accompany them. Hydrozircon also occurs in the lower ore-bearing horizon. Rich uranium mineralisation rarely occurs in faults cutting the U-Mo mineralised horizons in the western part of the Novoveská Huta deposit. Uranium and Mo mineralisation in these faults is represented by uraninite, coffinite and molybdenite.

2540 t U. Since 1992, all production in former East Germany has been derived from clean-up operations at the Königstein mine. In 2007, the production in the Königstein mine has been

History of Uranium Mining in Central Europe http://dx.doi.org/10.5772/intechopen.71962 13

The uranium mining in East Germany was concentrated in two main regions: the Ore Mts. region in Saxony (Schneeberg, Niederschlema-Alberoda, Johanngeorgenstadt, Schwarzenberg and Pöhla-Tellerhäuser) and the Ronneburg district in Thuringia. Small uranium deposits were evolved in the Cretaceous sandstones near the Königstein in Saxony [39–41]. Uranium deposits in the Ore Mts. region are hydrothermal vein deposits. In these ore deposits, three uraniferous mineral associations were established (quartz-calcite-pitchblende, carbonate-pitchblende-fluorite and bismuth-cobalt-nickel-silver-uranium). Uranium in these associations is represented by pitchblende, sooty pitchblende and coffinite. In veins of the Niederschlema-Alberoda deposit, coffinite constitutes up to 5% of the uranium content. The main ore deposit in this region was Niederschlema-Alberoda and it was one of the largest vein uranium deposits in the world, which has produced 73,900 t U. Other uranium deposits in the Ore Mts. region produced distinctly lower amount of uranium (Oberschlema 6700 t U, Johanngeorgenstadt 3600 t U, Pöhla-Tellerhäuser 1240 t U, Schwarzenberg 670 t U and

The Niederschlema-Alberoda uranium ore district is located in the Western Ore Mountains, in Germany, near the state boundary to Czech Republic. This ore district is evolved in the intersection of the SW-NE striking Loessnitz-Zwoenitz syncline with NW-SE trending Gera-Jáchymov fault zone. The Loessnitz-Zwoenitz syncline is one from sectional tectonic structures, which are ingredients of the Erzgebirge-Fichtelgebirge anticlinorium in the fold framework of the Saxothuringian Zone. The most important and central tectonic element of the Gera-Jáchymov fault zone is the vein structure Red Ridge (Roter Kamm), also defining the border between the Niederschlema-Alberoda ore district in NE and the Schneeberg uranium deposit in SW. In the Loessnitz-Zwoenitz syncline, predominantly Upper Ordovician-Silurian-Middle Devonian "productive" rocks are folded into Lower Ordovician schists of the northern edge zone of the Erzgebirge-Fichtelgebirge anticlinorium. The rock series of the "productive unit" are phyllites with intercalations of metamorphosed black shales and metacarbonates. The uranium-bearing veins occur in the contact metamorphic zone of the syncline beneath the late-Variscan Aue granite pluton. This granite body, located within the Gera-Jáchymov fault zone, intruded early-Variscan metasediments, especially low-grade garnet phyllites and medium-grade mica schists. The Aue granite body comprises various biotite granites. The Aue granite should have served as a major source for U accumulated in post-granitic deposits of Schneeberg and Schlema-

The uranium ore veins have a common thickness from 0.1 to 0.3 m with a maximum of 1 m. However, some ore veins show a massive pitchblende mineralisation with a thickness up to 2 m, which were mined down to a depth of about 2000 m. The hydrothermal mineralisation is usually divided into three main stages. The most important is first pitchblende-quartzcalcite-fluorite-sulphide stage. The second, post-Variscan stage contains dolomite-selenidepitchblende mineral association. For the third, Bi-Co-Ni stage, the predominance of arsenides

38 t U [31].

Schneeberg 160 t U).

Alberoda ore districts.

Some small uranium deposits and occurrences were found also in the other West Carpathian geological units in Slovakia, namely in the Hronicum (Vikartovce, Kravany, Švábovce), Tatricum (Kálnice, Selec) and the Veporicum. All these geological units could be distinguished into two morphological types of uranium mineralisation, namely stratiform mineralisation in the Permian volcanoclastic complexes and vein mineralisation evolved in tectonic zones (quartz-carbonate, quartz-gold-bearing veins) [37].

In 2012–2014, new exploration licences for uranium ore were active in the Slovak Republic. The most perspective exploration licence covers uranium mineralisation in Kuriškova, near Košice in the Eastern Slovakia. In this area, conventional resources in amount of 15,830 t U were calculated and identified. In the Novoveská Huta, resources in amount of 3488 t U are recently registered [31]. However, mining of both uranium deposits is recently blocked by various environmental activities.
