Mineralogical and geochemical characterization of rare-earth occurrences in the Serra do Mendes massif, Goiás, Brazil

2018 ◽  
Vol 188 ◽  
pp. 398-412 ◽  
Author(s):  
A.M. Zapata ◽  
N.F. Botelho
2021 ◽  
Author(s):  
Ao Su ◽  
et al.

Table S1: LA-ICP-MS U-Pb contents (ppm), and 238U/206Pb-207Pb/206Pb ratios of the microcrystalline-granular calcite (MGC) and blocky calcite (BC) in vein samples FSX1-1 and FSX1-2; Table S2: LA-ICP-MS rare earth element (REE) data (ppm) for calcite cements in vein samples FSX1-1 and FSX1-2.


2021 ◽  
Author(s):  
Ao Su ◽  
et al.

Table S1: LA-ICP-MS U-Pb contents (ppm), and 238U/206Pb-207Pb/206Pb ratios of the microcrystalline-granular calcite (MGC) and blocky calcite (BC) in vein samples FSX1-1 and FSX1-2; Table S2: LA-ICP-MS rare earth element (REE) data (ppm) for calcite cements in vein samples FSX1-1 and FSX1-2.


Minerals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 298 ◽  
Author(s):  
Francesco Putzolu ◽  
Armando Piccolo Papa ◽  
Nicola Mondillo ◽  
Maria Boni ◽  
Giuseppina Balassone ◽  
...  

The Abruzzi bauxite district includes the deposits located on the Campo Felice plateau and those of the Monti d’Ocre, which had been mined in the first part of the 20th century. Bauxite is of the karst type, with textures ranging between oolitic and oolitic-conglomeratic, the latter suggesting a partial reworking of evolved lateritic soils. The high contents of Al2O3 and Fe2O3 (average values 53.76 and 21.76 wt %, respectively) are associated with the presence of boehmite, hematite, and minor goethite. SiO2 and TiO2 have average values of 7.79 and 2.75 wt %, corresponding to the presence of kaolinite, anatase and rutile. Among the minor so-called “bauxitophile” elements V, Co, Ni, Cr and Zr, the most enriched is Cr, with an average value of 0.07 wt %. Nickel has an average value of 210.83 ppm. Vanadium shows an average value of 266.57 ppm, whereas the average Co concentration is 35.89 ppm. The total rare earth elements (REE) concentration in the sampled bauxite sites is variable between ca. 700 and 550 ppm. Among REEs, the most abundant element is Ce, with Ce anomalies commonly associated with authigenic REE-fluoro-carbonates, probably produced after the REEs remobilization from primary detrital minerals and their precipitation in neo-formed phases during the bauxitization process. Scandium and Ga occur in small amounts (57 and 60 ppm, respectively), but geochemical proxies of their remobilization and uptake in neo-formed minerals (Fe- and Al-(hydr)oxides, respectively) have been observed. The mean Eu/Eu* and Al2O3/TiO2 ratios and the Ni-Cr contents of the Abruzzi bauxites suggest that the parent rock of these deposits was a material of acid affinity, likely corresponding to volcanic tephra or eolic loess-type sands.


Clay Minerals ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 33-44 ◽  
Author(s):  
A. Lopez-Galindo ◽  
A. Ben Aboud ◽  
P. Fenoll Hach-Ali ◽  
J. Casas Ruiz

AbstractA mineralogical and geochemical study of the Gabasa outcrop (Huesca, NE Spain) was undertaken. It consists of Early Oligocene marly and clayey fluvial and lacustrine (playa-lake) sediments. The phases detected were quartz, amorphous silica, calcite, dolomite, palygorskite, illite, interstratified illite-smectite, Al-smectite and Mg-smectite. The palygorskite expands with ethyleneglycol. Statistical analysis of the geochemical data shows that the rare earth elements and transition trace elements are basically associated with the detrital phyllosilicates, although a considerable amount of the latter is contained in the palygorskite (ΣREE = 60–70 ppm, Cr+Co+Ni+V+Zn+Cu = 120–150 ppm), in contrast to the normally low values for neoformed minerals. This fact, together with the significant presence of Al and Fe in the palygorskite, suggest genesis involving alteration by dissolution of the 2:1 structure of the illite and/or Al-smectite, followed by re-ordering in a fibrous structure.


Author(s):  
G. M. Micha ◽  
L. Zhang

RENi5 (RE: rare earth) based alloys have been extensively evaluated for use as an electrode material for nickel-metal hydride batteries. A variety of alloys have been developed from the prototype intermetallic compound LaNi5. The use of mischmetal as a source of rare earth combined with transition metal and Al substitutions for Ni has caused the evolution of the alloy from a binary compound to one containing eight or more elements. This study evaluated the microstructural features of a complex commercial RENi5 based alloy using scanning and transmission electron microscopy.The alloy was evaluated in the as-cast condition. Its chemistry in at. pct. determined by bulk techniques was 12.1 La, 3.2 Ce, 1.5 Pr, 4.9 Nd, 50.2 Ni, 10.4 Co, 5.3 Mn and 2.0 Al. The as-cast material was of low strength, very brittle and contained a multitude of internal cracks. TEM foils could only be prepared by first embedding pieces of the alloy in epoxy.


2016 ◽  
Author(s):  
Antonio Lanzirotti ◽  
◽  
Stephen R. Sutton ◽  
Matt Newville ◽  
Jeffrey P. Fitts ◽  
...  

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