Geology and Mineralogy of Uranium Deposits

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (15 December 2018) | Viewed by 16381

Special Issue Editor

Institute of Rock Structure and Mechanics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
Interests: mineralogy; geochemistry; petrology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Uranium is one of the most important energy-related materials, with a current use almost entirely for generating electricity. In recent International Atomic Energy Agency (IAEA) classification, 15 types of uranium deposits were defined. In order of their economic ranking, the most significant uranium deposits are unconformity-related, sandstone, quartz-pebble conglomerates, granite-related and breccia complexes.

The goal of this Special Issue is to provide a platform for geoscientists dealing with geology and mineralogy of uranium deposits, in order to discuss new insights on their geological settings, composition and evolution of host rocks series (e.g., origin of episyenites, aceites and other altered rocks, origin of unconformity, sandstone and quartz-pebble conglomerate uranium deposits), mineral composition of main uranium minerals (uraninite, coffinite, brannerite) and classification of uranium deposits. There are expected innovative approaches applied to construction of new models of uranium ore deposits, discussion of physics-chemical conditions of their origin (e.g., fluid inclusion study, isotopes, detailed geochemistry in relation to behavior of HFS elements, especially REE, Y, Zr).

Dr. Miloš René
Guest Editor

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Keywords

  • geochemistry
  • mineralogy
  • uranium mineralization
  • uraninite
  • coffinite
  • brannerite
  • ore deposits

Published Papers (3 papers)

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Research

27 pages, 3603 KiB  
Article
Insights into B-Mg-Metasomatism at the Ranger U Deposit (NT, Australia) and Comparison with Canadian Unconformity-Related U Deposits
Minerals 2019, 9(7), 432; https://doi.org/10.3390/min9070432 - 14 Jul 2019
Cited by 6 | Viewed by 4002
Abstract
The Ranger deposit (Northern Territory, Australia) is one of the largest uranium deposits in the world. Uranium mineralisation occurs in crystalline basement rocks and is thought to belong to the unconformity-related category. In order to address the sources of magnesium and boron, and [...] Read more.
The Ranger deposit (Northern Territory, Australia) is one of the largest uranium deposits in the world. Uranium mineralisation occurs in crystalline basement rocks and is thought to belong to the unconformity-related category. In order to address the sources of magnesium and boron, and the temperature of the fluids related to boron and magnesium metasomatism that occurred shortly before and during the main uranium stage, in situ analyses of chlorite and tourmaline were carried out. The chemical composition of tourmaline shows an elevated X-site vacancy and a low Fetot/(Fetot + Mg) ratio typical of Mg-foitite. Uranium-related chlorite has relatively low Fe content (0.28–0.83 apfu) and high Mg content (3.08–3.84 apfu), with Si/Al = 1.08−1.22 and Mg/(Mg + Fetot) = 0.80−0.93 indicating a composition lying between the clinochlore and Mg-amesite fields. Chlorite composition indicates crystallisation temperature of 101–163 °C. The boron isotopic composition of tourmaline shows a range of δ11B values of ~1–9‰. A model is proposed involving two boron sources that contribute to a mixed isotopic signature: (i) evaporated seawater, which is typically enriched in magnesium and boron (δ11B ~ 40‰), and (ii) boron from the crystalline basement (δ11B ~ −30 to +10‰), which appears to be the dominant source. Collectively, the data indicate similar tourmaline chemistry but significant differences of tourmaline boron isotopic composition and chlorite chemistry between the Ranger deposit and some of the Canadian unconformity-related uranium deposits. However, lithogeochemical exploration approaches based on identification of boron- and magnesium-enriched zones may be usefully applied to uranium exploration in the Northern Territory. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Uranium Deposits)
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23 pages, 11391 KiB  
Article
The Mineral Chemistry of Chlorites and Its Relationship with Uranium Mineralization from Huangsha Uranium Mining Area in the Middle Nanling Range, SE China
Minerals 2019, 9(3), 199; https://doi.org/10.3390/min9030199 - 26 Mar 2019
Cited by 22 | Viewed by 5832
Abstract
The Huangsha uranium mining area is located in the Qingzhangshan uranium-bearing complex granite of the Middle Nanling Range, Southeast China. This uranium mining area contains three uranium deposits (Liangsanzhai, Egongtang, and Shangjiao) and multiple uranium occurrences, showing favorable mineralization conditions and prospecting potential [...] Read more.
The Huangsha uranium mining area is located in the Qingzhangshan uranium-bearing complex granite of the Middle Nanling Range, Southeast China. This uranium mining area contains three uranium deposits (Liangsanzhai, Egongtang, and Shangjiao) and multiple uranium occurrences, showing favorable mineralization conditions and prospecting potential for uranium mineral resources. Chloritization is one of the most important alteration types and prospecting indicators in this mining area. This study aims to unravel the formation environment of chlorites and the relationship between chloritization and uranium mineralization, based on detailed field work and petrographic studies of the wallrock and ore samples from the Huangsha uranium mining area. An electron probe microanalyzer (EPMA) was used in this study to analyze the paragenetic association, morphology, and chemical compositions of chlorite, to classify chemical types and to calculate formation temperatures and n(Al)/n(Al + Mg + Fe) values of chlorite. The formation mechanism and the relationship with uranium mineralization of the uranium mining area are presented. Some conclusions from this study are: (1) There are five types of chlorites, including the chlorite formed by the alteration of biotite (type-I), by the metasomatism of feldspar with Fe–Mg hydrothermal fluids (type-II), chlorite vein/veinlet filling in fissures (type-III), chlorite closely associated with uranium minerals (type-IV), and chlorite transformed from clay minerals by adsorbing Mg- and Fe-components (type-V). (2) The chlorite in the Huangsha uranium mining area belongs to iron-rich chlorite and is mainly composed of chamosite, partly clinochlore, which are the products of multiple stages of hydrothermal action. The original rocks are derived from argillite, and their formation temperatures vary from 195.7 °C to 283.0 °C, with an average of 233.2 °C, suggesting they formed under a medium to low temperature conditions. (3) The chlorites were formed under reducing conditions with low oxygen fugacity and relatively high sulfur fugacity through two formation mechanisms: dissolution–precipitation and dissolution–migration–precipitation; (4) The chloritization provided the required environment for uranium mineralization, and promoted the activation, migration, and deposition of uranium. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Uranium Deposits)
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23 pages, 9065 KiB  
Article
Uraninite, Coffinite and Ningyoite from Vein-Type Uranium Deposits of the Bohemian Massif (Central European Variscan Belt)
Minerals 2019, 9(2), 123; https://doi.org/10.3390/min9020123 - 19 Feb 2019
Cited by 11 | Viewed by 5529
Abstract
Uraninite-coffinite vein-type mineralisation with significant predominance of uraninite over coffinite occurs in the Příbram, Jáchymov and Horní Slavkov ore districts and the Potůčky, Zálesí and Předbořice uranium deposits. These uranium deposits are hosted by faults that are mostly developed in low- to high-grade [...] Read more.
Uraninite-coffinite vein-type mineralisation with significant predominance of uraninite over coffinite occurs in the Příbram, Jáchymov and Horní Slavkov ore districts and the Potůčky, Zálesí and Předbořice uranium deposits. These uranium deposits are hosted by faults that are mostly developed in low- to high-grade metamorphic rocks of the basement of the Bohemian Massif. Textural features and the chemical composition of uraninite, coffinite and ningyoite were studied using an electron microprobe. Collomorphic uraninite was the only primary uranium mineral in all deposits studied. The uraninites contained variable and elevated concentrations of PbO (1.5 wt %–5.4 wt %), CaO (0.7 wt %–8.3 wt %), and SiO2 (up to 10.0 wt %), whereas the contents of Th, Zr, REE and Y were usually below the detection limits of the electron microprobe. Coffinite usually forms by gradual coffinitization of uraninite in ore deposits and the concentration of CaO was lower than that in uraninites, varying from 0.6 wt % to 6.5 wt %. Coffinite from the Jáchymov ore district was partly enriched in Zr (up to 3.3 wt % ZrO2) and Y (up to 5.5 wt % Y2O3), and from the Potůčky uranium deposit, was distinctly enriched in P (up to 8.8 wt % P2O5), occurring in association with ningyoite. The chemical composition of ningyoite was similar to that from type locality; however, ningyoite from Potůčky was distinctly enriched in REE, containing up to 22.3 wt % REE2O3. Full article
(This article belongs to the Special Issue Geology and Mineralogy of Uranium Deposits)
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