nepheline syenite
Recently Published Documents


TOTAL DOCUMENTS

244
(FIVE YEARS 35)

H-INDEX

21
(FIVE YEARS 3)

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1163
Author(s):  
Hong Wang ◽  
Yong Tang ◽  
Yu-Sheng Xu ◽  
Hui Zhang ◽  
Zheng-Hang Lv ◽  
...  

The Shuangshan alkaline complex located in the Henan province of China is a newly discovered, potentially giant niobium (Nb) deposit. A variety of Nb-bearing minerals including pyrochlore, zircon, and titanite have been identified in this deposit. Distinct textural and chemical differences of pyrochlore and zircon indicate that both have different origins. The magmatic pyrochlore and zircon both have euhedral grains with small sizes. On the other hand, hydrothermal pyrochlore is mainly intergrown on the edge or inside of hydrothermal zircon in the form of an aggregate. Compared with magmatic pyrochlore, the contents of F, Ca, and Na in hydrothermal pyrochlore are obviously high. The texture and composition of hydrothermal pyrochlore and zircon indicate that Ca-bearing hydrothermal alteration resulted in the migration of Nb from Nb-bearing zircon and the reprecipitation of Nb to form aggregate pyrochlore. However, the quantitative calculation shows that the amount of Nb migrated from zircon is very small. Therefore, this study suggests that hydrothermal alteration plays a certain role in the redistribution of Nb, but the enrichment of Nb is limited.


Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1385
Author(s):  
Thiago Assis Rodrigues Nogueira ◽  
Bruno Gasparoti Miranda ◽  
Arshad Jalal ◽  
Luís Gustavo Frediani Lessa ◽  
Marcelo Carvalho Minhoto Teixeira Filho ◽  
...  

Some silicate rocks are a rich source of potassium (K), with the possibility for use in agriculture. The present study aimed to evaluate the agronomic efficiency index (AEI) of nepheline syenite (NS) and phonolite (PN) rocks in comparison with potassium chloride (KCl) as a K source in maize production. An experiment was conducted in a greenhouse in Ilha Solteira, São Paulo, Brazil. A maize hybrid was grown in 8 L pots filled with 6 kg of soil with a low K concentration and contrasting physical attributes (medium and sandy texture). A completely randomized design in a 3 × 6 factorial scheme was used, consisting of three K sources (NS, PN, and KCl) and six rates (0, 50, 100, 150, 200, and 400 mg kg−1) with four replications. All plants were harvested 45 days after emergence to evaluate biomass production, macronutrient (N, P, K, Ca, Mg, and S) concentration and uptake, stem diameter, and leaf chlorophyll index. After crop harvest, soil was collected for further chemical evaluation, which included organic matter (OM), pH, cation exchange capacity (CEC), H+Al, Al, sum of bases (SB), base saturation (BS), P, K, Ca, Mg, and S. In addition, AEI of NS and PN were also verified in relation to KCl. The application of NS and PN had a similar effect on soil chemical attributes (MO, pH, SB, CEC, and BS) as well as on the concentrations of K, Ca, Mg, and S, in both soils. The increase in NS and PN rates provided linear growth of shoot dry matter. Leaf macronutrient concentrations were similar for NS and PN compared to KCl. All three K sources (NS, PN, and KCl) increased K accumulation in maize plants. Maize treated with KCl had the largest AEI, followed by PN and NS. However, the results indicated similar AEI with both rocks as a K source for maize, especially with application of the highest K rates. This research demonstrated the efficiency of NS and PN as alternative K sources for maize.


Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 734
Author(s):  
Maria Bagani ◽  
Efthymios Balomenos ◽  
Dimitrios Panias

The increasing demand for aluminum in conjunction with the limited available bauxite deposits in Europe results in the dire need for the evaluation of alternative raw materials for the whole value chain of alumina production. The present paper focuses on the possible use of nepheline syenite, originated as a mine byproduct, in alumina production through leaching with an azeotropic HCl solution. Previous work on nepheline syenite dissolution focused more on the extraction of potassium and sodium values. In this work, emphasis is given at the characteristics and leachability of aluminum content phases by applying a high temperature HCl leaching in untreated material. From this point of view, leaching experiments were conducted on nepheline syenite, at a temperature range of 90 °C to 150 °C and with aqueous azeotropic HCl solution. Leaching, in the aforementioned conditions, is a process, characterized by medium aluminum dissolution. The results show that the aluminum-bearing phases that withstand the dissolution process are mainly the ones of sodium and potassium feldspars.


2021 ◽  
Author(s):  
Maciej Jaranowski ◽  
Bartosz Budzyń ◽  
Gabriela A. Kozub-Budzyń ◽  
Jiří Sláma ◽  
Josef Klomínský

<p>Stability relations of the REE-bearing accessory phases and alteration processes in the cancrinite-bearing nepheline syenite from the Čistá pluton (the center of the upper-crustal Tepla–Barrandian unit, Bohemian Massif, Czech Republic) were studied. Observations of rock microtextures, quantitative analyses of minerals and compositional X-ray mapping were performed using electron probe microanalysis (EPMA). The primary REE-bearing accessory minerals assemblage includes monazite-(Ce) associated with gadolinite-group minerals (i.e. gadolinite-(Ce) and gadolinite-(Y)), which were partially replaced by britholite-(Ce), bastnäsite-(Ce), aggregates of fine-grained REE-bearing phases (possibly fluorapatite and/or britholite-(Ce)) and, rarely, cerianite. K-feldspar and albite form intergrowths or symplectites with REE-phases in the investigated reaction microtextures. Furthermore, the zircon crystals demonstrate oscillatory zoning and/or extensive patchy zoning due to alteration processes. The alteration of accessory minerals are interpreted as driven by K- and Na-bearing alkali fluids with high CO<sub>2</sub> activity during late- to post-magmatic processes.</p><p>Acknowledgements: This work was supported by the National Science Centre research grant no. 2017/27/B/ST10/00813.</p>


2021 ◽  
Vol 130 (1) ◽  
Author(s):  
M G Thakkar ◽  
Gaurav Chauhan ◽  
Yash Shah ◽  
Chirag Jani ◽  
Bhavyata Chavada ◽  
...  

Author(s):  
G. Wie-Addo ◽  
A. H. Jones ◽  
S. Palmer ◽  
V. Starinieri ◽  
J. Renshaw ◽  
...  

AbstractThe influence of inorganic minerals (colemanite and nepheline syenite) as additives for sustainable clay brick manufacture has been examined. Each additive was added at 4 wt% to 96 wt% brick clay and samples were fired to 950 °C and 1040 °C and then compared with samples of 100% brick clay. Multiple analytical techniques (X-ray fluorescence, dilatometry, boiling water absorption, volumetric shrinkage, and mercury porosimetry) were used for analysis. Dilatometry shows that the additives influenced the temperature at which shrinkage began and the extent of that shrinkage. The use of colemanite reduced the temperature at which the shrinkage began by 120 °C and nepheline syenite reduced it by 20 °C. A linear shrinkage in dilatometry of 1% (from the maximum expanded length) was achieved at 1000 °C for 100% clay, 875 °C for colemanite additions and 970 °C for nepheline syenite additions. However, for samples fired at 1040 °C for 2 h colemanite containing samples had significantly lower volumetric shrinkage and higher water absorption than 100% clay and nepheline syenite samples, suggesting the presence of higher amounts of open porosity caused by the decomposition of the colemanite on heating. Samples containing nepheline syenite had a lower volumetric shrinkage but also a marginally lower water absorption than the 100% clay. The further optimisation of these or similar additives could potentially provide energy saving opportunities and reductions in CO2 emissions for brick manufacturers.


2020 ◽  
Vol 20 (4) ◽  
Author(s):  
Daniel Adelino da Silva ◽  
Akihisa Motoki ◽  
Anderson Costa dos Santos ◽  
Julio Mendes ◽  
Fred Jourdan ◽  
...  

This article presents geochemical characteristics of the alkaline rocks of Rio Bonito intrusive complex, State of Rio de Janeiro, Brazil, which is constituted mainly by nepheline syenite. The fractional crystallisation of this magma decreases K2O/(Na2O + K2O) and increases (Na + K)/Al. The TiO2, Fe2O3*, MgO, CaO, and P2O5 contents indicate fractionation of titanite, ilmenite, and clinopyroxene or amphibole. The total rare earth elements (REEs) are high, and the REE pattern is linear with negative gradient. The nepheline syenite aplite has low REEs, concave REE pattern, and positive Eu anomaly. The ultrabasic and basic mela-nepheline syenite samples have total REEs and light REEs higher than the felsic alkaline rocks. Therefore, the nepheline syenite magma is not derived directly from the alkaline ultrabasic magma. Laser-spot step‑heating 40Ar/39Ar ages for biotite and amphibole are 65.03 ± 0.70 and 65.03 ± 0.46. U-Pb ages LA-ICP-MS for two samples are 65.49 ± 0.30 and 65.18 ± 0.30. Values of εHf are negative for both samples, indicating an important crustal component in the evolution of Rio Bonito.


Sign in / Sign up

Export Citation Format

Share Document