Topic
Torbernite
About: Torbernite is a research topic. Over the lifetime, 66 publications have been published within this topic receiving 1022 citations. The topic is also known as: chalcolite.
Papers published on a yearly basis
Papers
TL;DR: In this paper, the authors synthetise la torbernite, the zeunerite, and the metazeunerite using the facteurs F2 for toutes les reflexions uniques.
Abstract: Nous avons synthetise la torbernite, Cu[(UO 2 )(PO 4 )] 2 (H 2 O) 1 2 , la zeunerite, Cu[(UO 2 )(AsO 4 )] 2 (H 2 O) 1 2 , la metatorbernite, Cu[(UO 2 )(PO 4 )] 2 (H 2 O) 8 , et la metazeunerite, Cu[(UO 2 )(AsO 4 )] 2 (H 2 O) 8 , par diffusion dans des gels ou bien par voie hydrothermale Les intensites des raies en diffraction X sur monocristal ont ete mesurees a temperature ambiante en utilisant un rayonnement MoKa et un detecteur de type CCD Nous avons resolu la structure des quatre composes par methodes directes, avec affinement sur matrice entiere par techniques de moindres carres en utilisant les facteurs F2 pour toutes les reflexions uniques jusqu'a un residu wR 2 (torbernite, zeunerite, metatorbernite et metazeunerite) de 56, 35, 48 et 51% pour toutes les donnees, et R1 de 24, 16, 20 et 23%, calcule pour 764, 468, 794 et 1447 reflexions uniques observees (‖F o ‖ ≥ 4σ F ), respectivement La torbernite est tetragonale, groupe spatial P4/nnc, a 70267(4), c 20807(2) A, V 10273(1) A 3 , Z = 2, D c a l c 3264(1) g/cm 3 La zeunerite est isostructurale avec la torbernite, a 71797(3), c 20857(1) A, V 10751(1) A 3 , Z= 2, D c a l c 3391(1) g/cm 3 La structure de la metatorbernite a ete determinee a partir d'un cristal macle par meroedrie Elle est tetragonale, groupe spatial P4/n, a 69756(5), c 17349(2) A, V 8442(1) A 3 , Z = 2, D c a l c 3689(1) g/cm 3 La metazeunerite est isostructurale avec la metatorbernite, a 71094(1), c 17416(1) A, V 8803(1) A 3 , Z = 2, D c a l c 3869(1) g/cm 3 ; le cristal qui a servi a l'ebauche aussi est macle Ces mineraux contiennent un feuillet de type autunite, de composition [(UO 2 )(PO 4 )] - , dans lequel il y a partage des coins equatoriaux des bipyramides carrees a uranyle avec des tetraedres de phosphate Dans chacune des structures, les cations Cu 2 + sont situes entre les feuillets dans des octaedres rendus difformes (4 + 2) a cause de l'effet de Jahn-Teller, avec des liaisons courtes a quatre groupes H 2 O dans un agencement carre planaire, et deux liaisons plus longues aux atomes d'oxygene des ions uranyle Un groupe H 2 O symetriquement independant est present dans chaque structure, lie seulement par liaisons hydrogene, et dans la torbernite (et la zeunerite) forme des agencements planaires carres de groupes interstitiels de H 2 O par-dessus et par-dessous les plans contenant les cations Cu 2 + L'affinement des quatre structures avec certaines contraintes a propos des longueurs des liaisons impliquant l'hydrogene a mene a des descriptions cristallochimiquement raisonnables des liaisons hydrogene
109 citations
TL;DR: Raman microscopy shows excellent band separation enabling the separation and identification of bands attributed to (UO2)2+ units, PO4 and AsO4 units.
75 citations
TL;DR: Mrazek et al. as discussed by the authors studied the supergene mineralization of the hydrothermal vein uranium deposit Medvědin (Krkonose Mts., northern Czechia) using powder XRD, EPMA, IR-spectroscopic and thermal analysis, contributing significantly to the clarification of their crystal chemistry.
Abstract: 3 �InstituteofEarthSciences,�FacultyofScience,�MasarykUniversity,�Kotlařska�2,�611�37�Brno,�CzechRepublic * �Correspondingauthor † �DedicatedtoeverlastingmemoryofoutstandingmineralogistIng.�ZdeněkMrazek,�CSc.�(1952-1984) Supergene mineralization of the hydrothermal vein uranium deposit Medvědin (Krkonose Mts., northern Bohemia) is rather varied both in number of the mineral phases and their chemical variation. The supergene minerals agardite- (Y), autunite/metaautunite, dewindtite, churchite-(Y), kasolite, new unnamed phase Pb(Ce,REE) 3 (PO 4 ) 3 (OH) 2 . nH 2 O, parsonsite, phosphuranylite, plumbogummite, pseudomalachite, pyromorphite, saleeite, torbernite/metatorbernite and uranophane were studied using powder XRD, EPMA, IR-spectroscopic and thermal analysis, contributing significantly to the clarification of their crystal chemistry. The alteration mineral assemblage consisting mostly of uranyl phosphates and silicates exhibits relatively high contents of REE and Pb. Minerals with a composition corresponding to pure mine- ral end-members have not been observed; instead most of the studied phases represent members of isomorphic series. Studied mineral assemblage is a stable association in surface conditions resulting apparently from a long-term alteration of the primary uranium mineralization.
52 citations
TL;DR: In this paper, three different supergene U mineral successions, referred to in the current study as pathways I to III, were identified, and limonite-cored torbernite was described for the first time.
Abstract: Iron played a decisive part when uranyl phosphates (‘yellow U ores’) formed during supergene alteration of the aplitic and pegmatitic rocks of the Hagendorf Pegmatite Province. Three different supergene U mineral successions, referred to in the current study as pathways I to III, were identified. Pathway I began with the release of PO 4 2− by the dissolution of rockbridgeite and ended after short-distance transport under alkaline reducing or slightly acidic oxidizing conditions in the precipitation of bassetite. Pathway II is an advanced form of pathway I that did not stop with the precipitation of bassetite, but progressed by acidic Cu-bearing meteoric waters under oxidizing conditions up to the torbernite precipitation stage. Minor amounts of Mn or Ca may have led to a deviation from the normal pathway into the stability fields of lehnerite or autunite, respectively, both of which may occur either as solid solution series or in a layered intergrowth with torbernite. Limonite-cored torbernite has been described for the first time and only exists in pathway III. Unlike its counterpart pathways I and II, which appeared at the end of a complex polystage element recycling process of secondary Fe phosphates under fluctuating redox and pH conditions, limonite-cored torbernite resulted from a monostage transformation of primary ‘black Fe-U ore minerals’ under strongly oxidizing conditions and short-distance element transport. These restricted physicochemical conditions caused the immediate stabilization of the Fe-U-P system and by doing so the U-Pb ratios of the black ore progenitor were well preserved in the limonitic core. Torbernite was analysed for U, Th and Pb isotopes by laser ablation inductively coupled plasma mass spectrometry techniques. For one domain the data yielded a formation age of 4.55±0.02 Ma, which corresponds to Miocene-Pliocene weathering and geomorphological processes in the study area. A second domain gave a discordia with an upper intercept age of 549±12 Ma, interpreted to represent a thermal event at the Precambrian-Cambrian boundary. Ferrocolumbite is found exclusively in the mineralization of pathway III. Due to the proximity of ferrocolumbite to torbernite, limonite-cored torbernite probably inherited the 549 Ma age from ferrocolumbite during supergene alteration.
42 citations
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Performance Metrics
| Year | Papers |
|---|---|
| 2019 | 1 |
| 2018 | 1 |
| 2017 | 2 |
| 2016 | 1 |
| 2015 | 1 |
| 2014 | 2 |