Mechanism of Saleeite Formation at the Koongarra Secondary Ore Deposit

1995 ◽  
Vol 412 ◽  
Author(s):  
Takashi Murakami ◽  
Hiroshi Isobe ◽  
Toshihiko Ohnuki ◽  
Tsutomu Sato ◽  
Nobuyuki Yanase ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Host Rock ◽  
Thermodynamic Calculations ◽  
Accessory Mineral ◽  
Uranium Mineral ◽  
Ore Deposit ◽  
Rock Samples ◽  
Iron Minerals ◽  
Ground Waters ◽  
20 Nm

AbstractRock samples in the secondary ore deposit at Koongarra, Australia, were examined mineralogically to clarify the formation mechanism of saléeite (Mg(UO2)2(PO4)2.10H2O), a major secondary uranium mineral in the secondary ore deposit. Sklodowskite (MgSi2U2O11.7H2O) veinlets, present upstream of the ore deposit, are partially replaced by saléeite. Most grains of apatite (Ca5(P04)3F), an accessory mineral of the host rock, are also replaced by saléeite. Thermodynamic calculations by EQ3NR showed that the present Koongarra ground waters are undersaturated with respect to saléeite and also suggested that saléeite can be precipitated under the condition of higher U or P concentrations. Such conditions can be created at the reaction interfaces of dissolving sklodowskite, which releases U, or dissolving apatite, which releases P. The present study indicates that saléeite is formed by local microscale saturation upstream of the secondary ore deposit, which is different from the formation mechanism of saléeite downstream of the ore deposit, where saléeite microcrystals of 1 – 20 nm in size form by catalysis on iron minerals, the weathering products of the host rock.

Uranium Fixation During Uranium Migration Under an Oxidizing Condition

1994 ◽  
Vol 353 ◽  
Author(s):  
Takashi Murakami ◽  
Katsuyuki Tsuzuki ◽  
Tsutomu Sato ◽  
Hiroshi Isobe ◽  
Toshihiko Ohnuki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Rock Specimen ◽  
Uranium Mineral ◽  
Ore Deposit ◽  
Iron Minerals ◽  
Transmission Electron ◽  
Uranium Migration ◽  
20 Nm

AbstractA rock specimen, collected downstream of the Koongarra uranium ore deposit, Australia, was examined mainly by high resolution transmission electron microscopy in order to understand the uranium fixation mechanism. Uranium was found to exist as saleeite (Mg(UO2)2(PO4)2.10H2O) microcrystals of 1 – 20 nm scattered between iron minerals (mainly goethite and hematite) of 2 – 50 nm. The microtextural relationship between saléeite and the iron minerals revealed that the iron minerals function as catalyst for the formation of saléeite. The intermediate metamict microstructures of the saléeite microcrystals are consistent with the estimated formation age of saléeite, 1 to 3 × 106 years. Uranium has been, thus, fixed as saléeite downstream as well as in the secondary ore deposit. Saléeite in the secondary ore deposit showed completely periodic to fully metamict microstructures, suggesting that saléeite, a major uranium mineral in the secondary ore deposit, probably began to form a few million years ago and continued to form for the next million years.

Effects of Chlorite Alteration on Uranium Redistribution in Koongarra, Australia

1990 ◽  
Vol 212 ◽  
Author(s):  
Takashi Murakami ◽  
Hiroshi Isobe ◽  
Robert Edis
Keyword(s):  
Diffraction Study ◽  
Host Rock ◽  
Uranium Concentration ◽  
Major Constituent ◽  
X Ray Diffraction ◽  
Ore Deposit ◽  
X Ray ◽  
Uranium Ore ◽  
Iron Minerals ◽  
Uranium Migration

ABSTRACTThe relevance of alteration of chlorite, one of the major constituent minerals of the host rock to uranium ore at Koongarra, to the redistribution of uranium in the vicinity of the ore deposit has been examined. The chlorite alteration is produced by weathering; chlorite is transformed to vermiculite, through regularly interstratified chlorite/vermiculite. The Fe released from chlorite reprecipitates to form iron minerals, possibly ferrihydrite. Vermiculite is then replaced by kaolinite (and possibly smectite), further releasing Fe. On the millimeter scale, an alpha autoradiography study has shown that uranium concentrations are qualitatively proportional to the extent of the alteration; altered chlorite grains having higher uranium concentration. On the meter scale, the X-ray diffraction study has revealed that the abundances of chlorite, vermiculite, and kaolinite correspond well to the low, intermediate, and high uranium concentration zones, respectively. These suggest that the interaction of the uraniferous solution with chlorite causes the alteration of chlorite and the precipitation and sorption of uranium in the alteration products from the solution, and thus, the uranium migration is retarded at Koongarra.

scholarly journals Microfaunal Signals and Paleoenvironmental Reconstruction Sediments in Well Z-1, Offshore Dahomey Basin, South-Western Nigeria

2020 ◽  
pp. 50-61
Author(s):  
Anthonia Nwanese Asadu ◽  
Charles Ojonuba Ameh
Keyword(s):  
Gamma Ray ◽  
Accessory Mineral ◽  
Paleoenvironmental Reconstruction ◽  
Planktic Foraminifera ◽  
Rock Samples ◽  
Foraminiferal Species ◽  
Depositional Settings ◽  
Dahomey Basin ◽  
Abundance And Diversity ◽  
Gamma Ray Log

Fifty ditch cutting rock samples from well Z-1, OPL 310 offshore Dahomey basin, south western Nigeria were analyzed for their microfaunal and lithofacies content for the purpose of reconstructing the environment of deposition. Standard techniques of foraminifera slide processing and analysis was followed for the recovery of foraminifera while the gamma ray log complemented the rock samples for the lithofacies analysis. The lithological analysis revealed two lithofacies units in a generally fining upward sequence. The basal sandstone unit is characteristically milky white to brownish, coarse-pebbly grained, sub-angular to round and poorly to well sort with intercalation of shale. This unit is overlain by light to dark grey, moderately hard and non-fissile shale/mudstone sequence with intercalation of sand. Accessory mineral assemblage present in the formations includes mica flakes, glauconite pellets, carbonaceous detritus and ferruginous materials. The basal sandstone unit belong to the Oshosun Formation while the upper shaly unit is typical of Afowo Formation. Microfaunal study showed good recovery of abundant and well diversified planktic and benthic foraminiferal species. Forty-two (42) planktic, sixty-five (65) benthic calcareous and one benthonic arenaceous foraminiferal species were recovered. Micropaleontologically, Paleoenvironmental deductions were based primarily on the assemblage, abundance and diversity of benthic foraminiferal species and presence or absence of planktic foraminifera. Accessory mineral presence also aided the interpretations. Integration of lithological and micropaleontological synthesis enhanced the delineation of two environmental subzones over the analyzed interval, the outer neritic and the upper bathyal depositional settings corresponding to Afowo and Oshosun Formation respectively. A lowstand prograding wedge which is a good exploration target offshore was recognized between intervals 3400 ft to 3500 ft. In conclusion, the rock succession studied, penetrated Afowo and Oshosun Formations, and were deposited in an environment ranging from outer neritic to upper bathyal settings.

Mineralogical Study of Huashan Granite-Type Uranium Ore Deposit in Northeast of Guangxi

2012 ◽  
Vol 621 ◽  
pp. 17-22 ◽  
Author(s):  
Zhi Qiang Kang ◽  
Zuo Hai Feng ◽  
Yong Gao Huang ◽  
Hong Yi Chen ◽  
Wei Fu ◽  
...  
Keyword(s):  
Uranium Mineral ◽  
Ore Deposit ◽  
Granite Pluton ◽  
Uranium Ore ◽  
Mineralogical Characteristics ◽  
Granite Type ◽  
Mineralogical Study ◽  
Mineral Compositions ◽  
The Difference ◽  
Main Component

Huashan granite-type uranium ore deposit is originated within the Huashan granite pluton in northeast of Guangxi, the mineral (mineralization) occurrences already found include Changchong, Baishijiao and Caomiping. Previous studies are relatively weak, especially in mineralogical characteristics, in this paper, a detailed study of minerals has been carried out through EPMA and EDS, the results show that the uranium mineral compositions of the three mineral (mineralization) occurrences are significantly different, but all of them are of secondary uranium minerals, among them, the main component of Changchong mineral (mineralization) occurrence is (meta-) autunite, of Baijiaoshi mineral (mineralization) occurrence is kasolite, and of Caomiping mineral (mineralization) occurrence is torbernite and zeunerite, which reflect the difference of their minerals sources.

Conditions of formation of the iron-containing minerals, Hällefors silver mines, Bergslagen, Sweden

1986 ◽  
Vol 50 (355) ◽  
pp. 101-110 ◽  
Author(s):  
A. W. Jasiński
Keyword(s):  
Aqueous Solutions ◽  
Iron Oxides ◽  
Iron Ore ◽  
Silver Deposit ◽  
Ore Deposit ◽  
Iron Minerals ◽  
Sulphide Precipitation ◽  
Iron Ore Deposit ◽  
Two Stages

AbstractThe Hällefors silver deposit is regarded as a volcanogenic-exhalative iron ore deposit with dispersed amounts of Ag-Pb-Zn (±Cu) which has undergone secondary remobilization leading to the concentration of sulphides and sulphosalts. Based on data from the iron oxides and sulphides, the sulphide-sulphosalt mineralization is believed to have been formed in two stages. The first is characterized by the ranges 573-473 K and 2.25–1.5 kbar, higher gradient of changes of log aS2 with temperature and mostly sulphide precipitation; the second by the ranges 473–443 K, lower gradient of changes of log aS2 and mainly sulphosalt deposition. Assuming the precipitation was from fluids and aqueous solutions, possible conditions of formation of some of the iron minerals have been determined.

Formation of Secondary Uranium Minerals in the Koongarra Deposit, Australia

1993 ◽  
Vol 333 ◽  
Author(s):  
Hiroshi Isobe ◽  
Rodney C. Ewing ◽  
Takashi Murakami
Keyword(s):  
Northern Territory ◽  
Accessory Mineral ◽  
Migration Behavior ◽  
Graphite Layer ◽  
Uranium Mineral ◽  
Oxidation Condition ◽  
Uranyl Phosphates ◽  
Alteration Processes ◽  
Uranyl Silicates ◽  
Uranium Minerals

ABSTRACTSecondary uranium minerals from the Koongarra deposit, Northern Territory of Australia, were examined in order to understand the formation and alteration processes of the uranium minerals and their relevance to the migration behavior of uranium, lead, calcium and rare earth elements in the weathered zone. In most of the secondary ore zone, the only stable uranium mineral was saléeite (Mg(UO2)2(PO4)2·10H20), occurring as euhedral platy crystals up to 1 mm in length in veins and at surfaces. Apatite (Ca5(PO4)3F), an accessory mineral of the host rock, has saléeite reaction rims, suggesting formation at the expense of apatite. Ca-uranyl phosphates, such as autunite (Ca(UO2)2(PO4)2·10H2O), were not identified, and Ca-rich uranyl silicates are also absent in the primary ore zone. Pb-bearing uranyl phosphates were found only in the graphite layer cross-cutting the secondary ore zone. In the graphite layer, the local low oxidation condition and high hydrocarbonate content of ground water have affected the formation of uranium minerals and the migration behavior of uranium.

Measurement of Uranium Series Radionuclides in Rock and Groundwater at the Koongarra ore Deposit, Australia, by Gamma Spectrometry

1994 ◽  
Vol 353 ◽  
Author(s):  
Nobuyuki Yanase ◽  
Keiichi Sekine
Keyword(s):  
Gamma Rays ◽  
Gamma Spectrometry ◽  
Chemical Separation ◽  
Separation Procedure ◽  
Ore Deposit ◽  
Rock Samples ◽  
Absorption Correction ◽  
Groundwater Samples ◽  
Energy Gamma ◽  
Good Agreement

AbstractGamma spectrometry without any self-absorption correction was developed to measure low energy gamma rays emitted by uranium and actinium series radionuclides in rock samples and groundwater residues collected at the Koongarra ore deposit, Australia. Thin samples were prepared to minimize the self-absorption by uranium in the samples. The present method gave standard deviations of 0.9 to 18% for the measurements of concentrations of uranium and actinium series radionuclides. The concentrations of 238U, 230Th and 235U measured by gamma spectrometry were compared with those by alpha spectrometry that requires a complicated chemical separation procedure. The results obtained by both methods were in fairly good agreement, and it was found that the gamma spectrometry is applicable to rock and groundwater samples having uranium contents up to 8.1% (103 Bq/g) and 3 Bq/1 of 238U, respectively. The detection limits were calculated to be of the order of 10−2 Bq/g for rock samples and 10−2 Bq/1 for groundwater samples. The concentrations of uranium and actinium series radionuclides can be determined precisely in these samples using gamma spectrometry without any self-absorption correction.

A Modelling Study on the Fractionation of Uranium Among Minerals During Rock Weathering

1992 ◽  
Vol 294 ◽  
Author(s):  
Toshihiko Ohnuki ◽  
Takashi Murakami ◽  
Nobuyuki Yanase
Keyword(s):  
Sequential Extraction ◽  
Rock Weathering ◽  
Ore Deposit ◽  
Secondary Minerals ◽  
Iron Minerals ◽  
Irreversible Sorption ◽  
Rock Alteration ◽  
Weathering Process ◽  
Good Agreement ◽  
Modelling Study

ABSTRACTA modelling study has been carried out to understand the effect of rock alteration on the fractionation of uranium among coexisting minerals (chlorite, vermiculite, kaolinite, amorphous and crystalline iron minerals) at the Koongarra ore deposit, Australia. The model considers the chlorite weathering process, its mechanism and rate, and assumes the presence of reversible and irreversible sorption sites in the secondary minerals. The calculated uranium concentrations at the two different sites in the minerals were compared with the results of sequential extraction experiments. Good agreement between the calculated and observed uranium concentrations was obtained only when an appropriate fraction of uranium is fixed to the irreversible sorption sites of the altered clay minerals. However, a conventional Kd model gave inconsistent uranium concentrations. The calculated results show that the crystalline iron minerals sorb uranium during all stages of weathering, and that the uranium fractionation among the minerals varies with time until the end of the weathering.

Sur la notion de "types" de gisements metalliferes

1958 ◽  
Vol S6-VIII (3) ◽  
pp. 237-244
Author(s):  
Pierre Routhier
Keyword(s):  
Chemical Composition ◽  
Host Rock ◽  
Country Rock ◽  
Ore Deposits ◽  
Igneous Rocks ◽  
Ore Deposit ◽  
Ore Body ◽  
Enclosing Rocks

Abstract Limitations of existing classifications of ore deposits are examined, and a new "natural" classificationis proposed, based on "types." The types are based on the mineralogic and geologic characteristics of the ore deposit itself and of the host rock. Among the characteristics to be determined for the ore deposit itself are its hypogene paragenesis, superficial alteration, and the chemical composition and ore content of both the hypogene and supergene ore. The characteristics to be determined for the host rock relate to the lithology and stratigraphy of the enclosing rocks and the presence of contact alteration, if any; the form of the ore body in relation to the structure of the country rock; the nearby presence of igneous rocks; and age, if determinable. Descriptions can be completed by giving a list of examples of similar deposits with their age, if known, and pertinent genetic hypotheses.

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