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Crystallography and Mineralogy of Phosphates
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Crystallography and Mineralogy of Phosphates

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Crystallography and Physical Chemistry of Minerals & Nanominerals".

Deadline for manuscript submissions: closed (30 September 2020) | Viewed by 19689

Special Issue Editor

Dr. Rotiroti Nicola

E-Mail Website
Guest Editor
Department of Earth Sciences "Ardito Desio", University of Milan, Milan, Italy
Interests: mineralogy; crystallography; crystal chemistry; crystal structure refinement; single crystal X-ray diffraction

Special Issue Information

Dear Colleagues,

We are pleased to invite you to participate in a Special Issue of Minerals dedicated to Crystallography and Mineralogy of Phosphates. Phosphates are all around us—in fact, they are even inside us! This issue is the place where to write about phosphates as minerals. Mainly in nature, they display a large variety of structures, all with isolated (PO4) tetrahedral units, although they can build clusters, chains, sheets, and frameworks with octahedral units. Polyphosphates are common among synthetic compounds. Phosphates can be grouped as: (i) primary phosphates that have crystallized from a liquid; or (ii) secondary phosphates formed by the alteration of primary phosphates.

As there are several phosphate fields of interest, our Special Issue will cover the mineralogical and crystallographic aspect of a broad range of relevant topics, such as:

  • Phosphates as REE bearing minerals;
  • Petrographic relationships among phosphates and their chemical variation;
  • Paragenesis of pegmatite phosphates;
  • Alteration in phosphates;
  • Phosphates as gemstones;
  • Phosphates of biogenic materials;
  • High–low temperature;
  • High pressure.

The development of high-precision analytical techniques for mineralogical and crystallographic investigations is currently providing several instruments that may contribute to a new point of view for this topic. Therefore, multimethodological techniques are welcomed to explain the deep nature of these minerals.

The aim of this Special Issue is to collect novel research studies that can put new light on the characterization of any system of particular mineralogical and crystallographic interest in which phospates are involved.

Dr. Rotiroti Nicola
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Phosphates
  • Pegmatites
  • Framework minerals
  • Crystal chemistry
  • Crystal structure refinement
  • Crystal growth
  • Non-ambient conditions

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Published Papers (6 papers)

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Research

24 pages, 9608 KiB  
Article
Trace Elements in Apatite as Genetic Indicators of the Evate Apatite-Magnetite Deposit, NE Mozambique
by Marek Slobodník, Veronika Dillingerová, Michaela Blažeková, Monika Huraiová and Vratislav Hurai
Minerals 2020, 10(12), 1125; https://doi.org/10.3390/min10121125 - 14 Dec 2020
Cited by 2 | Viewed by 3917
Abstract
The Evate deposit is a Neoproterozoic (~590 Ma) magnetite-apatite-carbonate body emplaced parallel to foliation of the Monapo granulite complex in NE Mozambique. A complicated history of the deposit is recorded in apatite textures visualized in cathodoluminescence (CL) images. In spite of different solid [...] Read more.
The Evate deposit is a Neoproterozoic (~590 Ma) magnetite-apatite-carbonate body emplaced parallel to foliation of the Monapo granulite complex in NE Mozambique. A complicated history of the deposit is recorded in apatite textures visualized in cathodoluminescence (CL) images. In spite of different solid and fluid inclusions, mineral assemblages, and the CL textures, electron probe microanalyses indicate relatively consistent apatite compositions corresponding to fluorapatite (XF = 0.51–0.73, XOH = 0.21–0.47, XCl = 0.02–0.06) with limited belovite- and cesanite-type substitutions. Laser ablation inductively coupled plasma mass spectrometric analyses show that apatites from unaltered magnetite-forsterite-spinel ores are depleted in Y, REE, Ba, and Sr compared to apatites from carbonate-anhydrite ores. Hydrothermally overprinted apatites with complex patchy domain CL textures are enriched in Y-REE in greenish-grey zones, Fe-U-Th in blue zones, and Mn-Sr-Ba in brown domains. Observed CL-emissions in the Evate apatites result from very subtle variations in REE, Mn, and U contents controlled by the variability of redox conditions. The decreased Th:U ratio in the hydrothermally overprinted apatites reflects the oxidation and partial removal of U4+ from the apatite structure during the interaction with oxidizing aqueous fluids capable of transporting U6+. Flat, LREE (La-Sm)-enriched chondrite-normalized patterns with Eu/Eu* = 0.7–1.4 and Ce/Ce* = 0.9–1.5, together with concentrations of diagnostic trace elements (Sr, Mn, Y, REE) are consistent with apatites from magmatic carbonatites and phoscorites. This study corroborates that the Evate deposit is a post-collisional orogenic carbonatite genetically linked with mafic plutonic rocks intruding the Monapo granulite complex after granulite-facies metamorphism, and later overprinted by intensive hydrothermalism. The Evate apatite is peculiar in retaining its pristine magmatic signature despite the extensive hydrothermal-metasomatic alteration accompanied by dissolution-reprecipitation. Full article
(This article belongs to the Special Issue Crystallography and Mineralogy of Phosphates)
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18 pages, 5116 KiB  
Article
Occurrence of Sesquioxide in a Mid-Low Grade Collophane-Sedimentary Apatite Ore from Guizhou, China
by Jie Deng, Kecheng Zhang, Dongsheng He, Hengqin Zhao, Rachid Hakkou and Mostafa Benzaazoua
Minerals 2020, 10(11), 1038; https://doi.org/10.3390/min10111038 - 20 Nov 2020
Cited by 7 | Viewed by 2594
Abstract
Checking the presence of sesquioxide (Fe2O3, Al2O3) is helpful for its removal in advance. Therefore, the occurrence of sesquioxide in a mid-low grade calcareous-siliceous collophane ore (massive carbonate-apatite, also known as francolite) from Guizhou, China [...] Read more.
Checking the presence of sesquioxide (Fe2O3, Al2O3) is helpful for its removal in advance. Therefore, the occurrence of sesquioxide in a mid-low grade calcareous-siliceous collophane ore (massive carbonate-apatite, also known as francolite) from Guizhou, China was determined by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), field emission scanning electron microscope-energy dispersive X-ray spectrometry (FESEM-EDX) and Mineral Liberation Analyzer (MLA). The results show that iron mainly occurs as pyrite FeS2, goethite FeO(OH) and as substitution within dolomite Ca(Mg,Fe)(CO3)2, while aluminum is enriched in muscovite KAl2(AlSi3O10)(OH)2 and also found in apatite (F,CO3)CaPO4 and calcite CaCO3 due to isomorphism or adsorption. All these minerals are fine-grained, among which pyrite and goethite tend to be enriched in larger particles. Intergrowth is predominant in the six minerals’ locking. Pyrite is mainly intergrown with calcite, biotite and also included in apatite and muscovite, while the monomer pyrite appears as semi-automorphic fine grain with the liberation of 56.1%. Apatite particles are mainly intergrown with quartz and calcite. Most of goethite, dolomite, muscovite and calcite form intergrowth with apatite, with contents of 21.7%, 11.1%, 19.5% and 41%, respectively. The removal of pyrite, goethite, dolomite, muscovite and calcite in the ore is the key to reduce the contents of Fe2O3 and Al2O3. In the subsequent beneficiation, the ore must be fully ground. In addition to flotation, magnetic separation can also be considered to remove part of iron in ore. For the removal of aluminum from apatite, leaching method can be considered. Full article
(This article belongs to the Special Issue Crystallography and Mineralogy of Phosphates)
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9 pages, 1672 KiB  
Article
Wardite (NaAl3(PO4)2(OH)4·2H2O) at High Pressure: Compressional Behavior and Structure Evolution
by G. Diego Gatta, Davide Comboni, Paolo Lotti, Alessandro Guastoni, Nicola Rotiroti and Michael Hanfland
Minerals 2020, 10(10), 877; https://doi.org/10.3390/min10100877 - 1 Oct 2020
Viewed by 2291
Abstract
The high-pressure behavior of wardite, NaAl3(PO4)2(OH)4·2H2O (a = 7.0673(2) Å, c = 19.193(9) Å, Sp. Gr. P41212), has been investigated by in-situ single-crystal synchrotron diffraction experiments up [...] Read more.
The high-pressure behavior of wardite, NaAl3(PO4)2(OH)4·2H2O (a = 7.0673(2) Å, c = 19.193(9) Å, Sp. Gr. P41212), has been investigated by in-situ single-crystal synchrotron diffraction experiments up to 9 GPa, using a diamond anvil cell under quasi-hydrostatic conditions. This phosphate does not experience any pressure-induced phase transition, or anomalous compressional behavior, within the pressure-range investigated: its compressional behavior is fully elastic and all the deformation mechanisms, at the atomic scale, are reversible upon decompression. A second-order Birch–Murnaghan Equation of State was fitted to the experimental data, weighted by their uncertainty in pressure (P) and volume (V), with the following refined parameters: V0 = 957.8(2) Å3 and KV0 = −V0(∂P/∂V)P0,T0 = 85.8(4) GPa (βV0 = 1/KV0 = 0.01166(5) GPa−1). Axial bulk moduli were also calculated, with: K0(a) = 98(3) GPa (β0(a) = 0.0034(1) GPa−1) and K0(c) = 64(1) GPa (β0(c) = 0.0052(1) GPa−1). The anisotropic compressional scheme is: K0(a):K0(c) = 1.53:1. A series of structure refinements were performed on the basis of the intensity data collected in compression and decompression. The mechanisms at the atomic scale, responsible for the structure anisotropy of wardite, are discussed. Full article
(This article belongs to the Special Issue Crystallography and Mineralogy of Phosphates)
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18 pages, 6205 KiB  
Article
Mineralogy and Geochemistry of Sr-Bearing Phosphates from the Nanping No. 31 Pegmatite (SE China): Implications for Sr Circulation and Post-Magmatic Processes in Granitic Systems
by Can Rao, Ru-Cheng Wang, Frédéric Hatert, Run-Qiu Wu and Qi Wang
Minerals 2020, 10(6), 541; https://doi.org/10.3390/min10060541 - 16 Jun 2020
Cited by 3 | Viewed by 2534
Abstract
Although Rb/Sr ratio and Sr isotopes are routinely modeled to determine petrogenetic processes and sources for granitic systems, the post-magmatic path and crystallization of Sr in granitic systems have not been thoroughly elucidated to date. In this study, we present the petrography, chemical [...] Read more.
Although Rb/Sr ratio and Sr isotopes are routinely modeled to determine petrogenetic processes and sources for granitic systems, the post-magmatic path and crystallization of Sr in granitic systems have not been thoroughly elucidated to date. In this study, we present the petrography, chemical composition and isotopic 87Sr/86 of Sr-bearing phosphates from the Nanping No. 31 pegmatite in Southeastern China, helping to characterize post-magmatic stages and geochemical recirculation of Sr in granitic systems. K-feldspar and primary apatites occur as major “primary Sr minerals”, the occurrences of secondary Sr phosphates (strontiohurlbutite, palermoite and goyazite) and Sr-rich phosphates (apatites, hurlbutite, bertossaite and fluorarrojadite-(BaNa)) reflect the transport, concentration and recrystallization of Sr in granitic systems. The mobilization and recrystallization of Sr in granitic systems are mainly controlled by the variation in alkalinity of hydrothermal fluids. Two post-magmatic recirculations of Sr are proposed in the Nanping No. 31 pegmatite: (1) breakdown of the “primary Sr mineral” (K-feldspar and primary apatites) and crystallization of secondary Sr-bearing phases; and (2) replacement of secondary Sr-bearing phosphates and direct precipitation of later palermoite and goyazite from later Sr-rich fluids at low temperatures. The Sr isotope features of Sr-bearing phosphates suggest that the emplacement and consolidation processes of the Nanping pegmatite involved the participation of externally derived fluids. Full article
(This article belongs to the Special Issue Crystallography and Mineralogy of Phosphates)
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13 pages, 5378 KiB  
Article
The Chemical State and Occupancy of Radiogenic Pb, and Crystallinity of RW-1 Monazite Revealed by XPS and TEM
by Xu Tang, Qiu-Li Li, Bin Zhang, Peng Wang, Li-Xin Gu, Xiao-Xiao Ling, Chen-Hui Fei and Jin-Hua Li
Minerals 2020, 10(6), 504; https://doi.org/10.3390/min10060504 - 31 May 2020
Cited by 10 | Viewed by 3709
Abstract
Monazite ((Ce, La, Nd, Th)PO4) is one of the widely used minerals for U–Th–Pb dating in geochronology. To better understand the possible effects of radiogenic Pb on the in situ dating method, a natural monazite U–Th–Pb standard sample (RW-1) was chemically [...] Read more.
Monazite ((Ce, La, Nd, Th)PO4) is one of the widely used minerals for U–Th–Pb dating in geochronology. To better understand the possible effects of radiogenic Pb on the in situ dating method, a natural monazite U–Th–Pb standard sample (RW-1) was chemically and structurally characterized down to atomic scales by using the combination of Raman spectrum (RM), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The experimental results revealed that radiogenic Pb exists as Pb2+ and substitutes for the Ce site in the monazite crystal lattice. Moreover, TEM imaging demonstrated that monazite is well crystalline revealed by an atomic structure in most areas except for a few tiny defects, which are likely attributed to alpha self-healing from an electronic energy loss of α particles. The characterization of the chemical state and occupancy of radiogenic Pb, and the distribution of Pb and Th in monazite at the nanoscale and atomic scale could provide insight for us to understand the mechanisms of the nanogeochronology. Full article
(This article belongs to the Special Issue Crystallography and Mineralogy of Phosphates)
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14 pages, 16096 KiB  
Article
Fe-Al Phosphate Microcrystals in Pedogenic Goethite Pisoliths
by János Kovács, Éva Farics, Péter Szabó and István Sajó
Minerals 2020, 10(4), 357; https://doi.org/10.3390/min10040357 - 16 Apr 2020
Cited by 4 | Viewed by 4055
Abstract
In sedimentary rocks, Fe-Al phosphate minerals occur in different rocks and depositional environments. Herein, we present microcrystals of wavellite, crandallite, and cacoxenite from pedogenic goethite pisoliths and nodules. Pisoliths and nodules are generally dominated by Fe oxides and oxihydroxides. Frequently, pisoliths and nodules [...] Read more.
In sedimentary rocks, Fe-Al phosphate minerals occur in different rocks and depositional environments. Herein, we present microcrystals of wavellite, crandallite, and cacoxenite from pedogenic goethite pisoliths and nodules. Pisoliths and nodules are generally dominated by Fe oxides and oxihydroxides. Frequently, pisoliths and nodules demonstrate high phosphatization and a substantial contribution of allogenic detritus. The aim of our study is to present these remarkable crystals found in goethites. We describe the geochemistry and mineralogy of the pisoliths and try to interpret the possible paragenesis of the minerals. Loose ferruginous pisoliths and nodules are separated from the red paleosol and analyzed using field emission scanning electron microscope (FE-SEM) coupled with the energy dispersive X-ray detector (EDS), X-ray fluorescence spectroscopy (XRF), and X-ray powder diffraction (XRD) methods. The studied paleosols are weathered in a subtropical climate and the newly formed precipitation products, such as crandallite, wavellite, cacoxenite, and goethite, accumulate during the weathering of apatite. Full article
(This article belongs to the Special Issue Crystallography and Mineralogy of Phosphates)
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