scholarly journals Trace element fractionation between biotite, allanite, and granitic melt

2021 ◽  
Vol 176 (9) ◽  
Author(s):  
Patrick Were ◽  
Hans Keppler
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Rare Earths ◽  
Transition Metal Ions ◽  
Oxide Phases ◽  
Alkaline Earths ◽  
Trace Element Fractionation ◽  
Water Saturated ◽  
Granitic Melt ◽  
The Rare Earth

AbstractThe partitioning of a large suite of trace elements between biotite and water-saturated granitic melt was measured at 2 kbar and 700—800 ˚C. To reach equilibrium and to grow biotite crystals large enough for analysis, runs usually lasted from 30 to 45 days. In every charge, a few trace elements were initially doped at the 0.1—0.5 wt. % level and analyzed by electron microprobe after the run. First-row transition metal ions are highly compatible in biotite with Dbiotite/melt of 17 for Ti, 35 for V, 47 for Co, 174 for Ni, and 5.8 for Zn. A very notable exception is Cu with Dbiotite/melt < 0.9. This is likely one of the reasons why Cu is enriched together with Mo (Dbiotite/melt = 0.29) in porphyry deposits associated with intermediate to felsic plutons, while the other transition metals are not. Both Nb and Ta are mildly compatible in biotite with Dbiotite/melt being larger for Nb (3.69) than for Ta (1.89). Moderate (15—30%) biotite fractionation would be sufficient to reduce the Nb/Ta ratio from the chondritic value to the range observed in the continental crust. Moreover, the strong partitioning of Ti into biotite implies that already modest biotite fractionation suppresses the saturation of Ti-oxide phases and thereby indirectly facilitates the enrichment of Ta over Nb in the residual melt. The heavy alkalis, alkaline earths, and Pb are only mildly fractionated between biotite and melt (Dbiotite/melt = 3.8 for Rb, 0.6 for Cs, 0.6 for Sr, 1.8 for Ba, 0.7 for Pb). The rare earth elements are generally incompatible in biotite, with a minimum for Dbiotite/melt of 0.03–0.06 at Gd, Tb, and Dy, while both the light and heavy rare earths are less incompatible (e.g. Dbiotite/melt = 0.6 for La and 0.3 for Yb). This behavior probably reflects a partitioning into two sites, the K site for the light rare earths and the octahedral Mg site for the heavy rare earths. There is no obvious dependence of the rare earth partition coefficients on tetrahedral Al in the biotite, presumably because charge balancing by cation vacancies is possible. Allanite was found as run product in some experiments. For the light rare earths, Dallanite/melt is very high (e.g. 385 to 963 for Ce and Nd) and appears to increase with decreasing temperatures. However, the rather high solubility of allanite in the melts implies that it likely only crystallizes during the last stages of cooling of most magmas, except if the source magma is unusually enriched in rare earths.

China and the Geopolitics of Rare Earths

2017 ◽  
Author(s):  
Sophia Kalantzakos
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Resource Competition ◽  
Renewable Energy Sources ◽  
High Tech ◽  
Trade Dispute ◽  
Policy Responses ◽  
Economic Statecraft ◽  
The Rare Earth

In 2010, because of a geopolitical incident between China and Japan, seventeen elements of the periodic table known as rare earths became notorious overnight. An “unofficial” and temporary embargo of rare-earth shipments to Japan alerted the world to China’s near monopoly position on the production and export of these indispensable elements for high-tech, defense, and renewable energy sources. A few months before the geopolitical confrontation, China had chosen to substantially cut export quotas of rare earths. Both events sent shockwaves across the markets, and rare-earth prices skyrocketed, prompting reactions from industrial nations and industry itself. The rare-earth crisis is not a simple trade dispute, however. It also raises questions about China’s use of economic statecraft and the impacts of growing resource competition. A detailed and nuanced examination of the rare-earth crisis provides a significant and distinctive case study of resource competition and its spill-over geopolitical effects. It sheds light on the formulation, deployment, longevity, effectiveness, and, perhaps, shortsightedness of policy responses by other industrial nations, while also providing an example of how China might choose to employ instruments of economic statecraft in its rise to superpower status.

Investigation on the Rare Earth Terpyridyl System

1965 ◽  
Vol 20 (12) ◽  
pp. 1661-1664
Author(s):  
Shyama P. Sinha
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Infrared Studies ◽  
Spectrochemical Series ◽  
Breathing Vibration ◽  
The Rare Earth

The preparation of terpyridyl chelates of heavier rare earths of the type M (Terp) (NO3)3 ·n H2O(M = Tb — Yb and n = O —3) is described. The infrared studies of the solid chelates show the coordinated nature of both terpyridyl and nitrate groups. A spectrochemical series based on the shift of the “breathing” vibration of terpyridyl in the complexes is proposed.

scholarly journals China’s public policies toward rare earths, 1975–2018

2020 ◽  
Vol 33 (1-2) ◽  
pp. 127-151 ◽  
Author(s):  
Yuzhou Shen ◽  
Ruthann Moomy ◽  
Roderick G. Eggert
Keyword(s):  
Rare Earth ◽  
Environmental Degradation ◽  
Rare Earths ◽  
Chinese Economy ◽  
The State ◽  
Chinese Government ◽  
Mineral Industry ◽  
Policy Documents ◽  
Economic Background ◽  
The Rare Earth

AbstractThis paper summarizes and evaluates China’s policies toward the rare-earth industry from 1975 to 2018. We define five stages over this period and focus on China’s purpose, the underlying economic background in each stage, and the connections between stages. By reviewing a broad set of original policy documents, we find that the purpose of China’s policies has evolved, affected by the market players, the development of the mineral industry, and the state of the Chinese economy. Initially, the Chinese government encouraged the development of the upstream rare-earth sector. Since the early 1990s, China has focused on the development of downstream activities that use rare earths in the manufacture of intermediate and final products. Since the early 2000s, China has focused additionally on the problems of disorder in the rare-earth industry with particular reference to the environmental degradation caused by rare-earth production, as well as industrial reorganization to discourage unsanctioned production.

Optical Activation of Ion Implanted Rare-Earths

1993 ◽  
Vol 301 ◽  
Author(s):  
P.N. Favennec ◽  
H. L'haridon ◽  
D. Moutonnet ◽  
M. Salvi ◽  
M. Gauneau
Keyword(s):  
Rare Earth ◽  
Ion Implantation ◽  
Rare Earth Elements ◽  
Rare Earths ◽  
Annealing Temperature ◽  
Implantation Energy ◽  
Optical Activation ◽  
Energy Dose ◽  
The Rare Earth ◽  
Ion Implanted

ABSTRACTA review of the main results concerning the ion implantation of the rare-earth elements is given.To obtain the best optical activation of rare-earths, we attempt to optimize the implantation (energy, dose) and annealing (temperature, duration) conditions. The studied materials are Si, II-VI binaries (ZnTe, CdS), III-V binaries (GaAs, InP), III-V ternaries (GaAlAs, GaInAs) and III-V quaternaries (GaInAsP).

scholarly journals The isotopic constitution and atomic weights of the rare earth elements

1934 ◽  
Vol 146 (856) ◽  
pp. 46-55 ◽  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Positive Result ◽  
Rare Earths ◽  
Periodic Table ◽  
Resolving Power ◽  
Fundamental Importance ◽  
Lack Of Information ◽  
Isotopic Constitution ◽  
The Rare Earth

Hitherto the widest gap in our knowledge of the isotopic constitution of the elements has been in that part of the periodic Table containing rare earths. A means of obtaining the mass rays of these substances was discovered 10 years ago. By this it was possible to demonstrate the simplicity of lanthanum and praseodymium and to obtain a provisional analysis of the complex elements cerium and neodymium. Beyond these the only positive result was a faint blurr which suggested that erbium was complex and it was decided to postpone further attempts until an instrument of higher resolving power was available. When this was constructed it was naturally first applied to the numerous problems which appeared to be of more fundamental importance so that the complete lack of information on elements 62 to 76 remained.

scholarly journals On the ultra-violet spectrum of ytterbium

1906 ◽  
Vol 78 (522) ◽  
pp. 154-156
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Ultra Violet ◽  
The Subject ◽  
The Rare Earth

The rare earth, ytterbia, was discovered in 1878 by Marignac. In 1880 Nilson, in purifying Marignac’s ytterbia, found that it contained another earth which he named scandia. Cleve, and more recently his daughter Astrid Cleve, have worked much on ytterbia, and within the last few years M. Urbain has taken up the subject, and has succeeded in purifying ytterbia in larger quantities. During my own work on the fractionation of the rare earths I also have prepared and worked with ytterbia. Marignac, Nilson, Cleve, and Urbain have each presented me with some of their ytterbia. Nilson’s earth, sent in 1886, appears very pure. Unfortunately, there was only sufficient to enable me to photograph the part of its spectrum between wave-lengths 2400 and 2580.

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