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Properties of Melt and Minerals at High Pressures and High Temperatures

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A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Geochemistry and Geochronology".

Deadline for manuscript submissions: closed (24 January 2020) | Viewed by 53554

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Prof. Dr. Claudia Romano

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Dipartimento di Scienze, Università degli Studi Roma Tre, L.go San Leonardo Murialdo 1, 00146 Rome, Italy
Interests: magma physical and chemical properties; properties of melt and minerals at high pressures and high temperatures; spectroscopic studies of inorganic materials; spectroscopic studies on volatiles species; experimental volcanology and petrology; crystallization dynamics; rheology of magma; water solubility and speciation; structure of silicate melts; eruption dynamics

Special Issue Information

Dear Colleagues,

High pressure, high temperature mineralogy has long played an essential role in our understanding of planetary interiors. As developments in high-pressure, high-temperature methods continue to emerge, we continue to broaden our insights on how the properties of minerals vary with depth from crust to mantle to core. Along with comparable advances made to analytical methods, we have reached levels of accuracy and precision in the determination of properties at extreme conditions that allow for a much sharper comprehension of Earth’s and other planetary interiors. Silicate melts are critical components in nearly every igneous process, particularly at conditions of high pressure. During Earth’s period of accretion silicate melts served as transport media leading to its chemical differentiation and formation of the core, mantle and crust. Like many minerals, the physical properties of silicate melts can be very sensitive to pressure, especially at conditions favoring the transformation of tetrahedral cations to pentahedral and octahedral species. Unique compression and decompression mechanisms can be the cause of anomalous behavior in the density and viscosity of evolving magmatic systems. Our understanding of how silicate melts behave at depths of the Earth is vital because of our vulnerability to the volcanic activity at its surface as eruptions can vary widely in style, scale, duration and frequency.

Prof. Claudia Romano
Guest Editor

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Keywords

high-pressure
high-temperature
silicate melts
mineralogy
mineral physics
physical properties

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Published Papers (12 papers)

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Editorial

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7 pages, 198 KiB

Open AccessEditorial

Editorial for the Special Issue “Properties of Melt and Minerals at High Pressures and High Temperature”

by Claudia Romano

Minerals 2020, 10(8), 723; https://doi.org/10.3390/min10080723 - 18 Aug 2020

Cited by 1 | Viewed by 1914

Abstract

This Special Volume sets out to summarize knowledge in the rapidly developing area of the high-pressure and high-temperature properties and structure of silicate melts and minerals [...] Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

Research

Jump to: Editorial

13 pages, 1803 KiB

Open AccessArticle

The Viscosity and Atomic Structure of Volatile-Bearing Melilititic Melts at High Pressure and Temperature and the Transport of Deep Carbon

by Vincenzo Stagno, Veronica Stopponi, Yoshio Kono, Annalisa D’Arco, Stefano Lupi, Claudia Romano, Brent T. Poe, Dionysis I. Foustoukos, Piergiorgio Scarlato and Craig E. Manning

Minerals 2020, 10(3), 267; https://doi.org/10.3390/min10030267 - 16 Mar 2020

Cited by 7 | Viewed by 3674

Abstract

Understanding the viscosity of mantle-derived magmas is needed to model their migration mechanisms and ascent rate from the source rock to the surface. High pressure–temperature experimental data are now available on the viscosity of synthetic melts, pure carbonatitic to carbonate–silicate compositions, anhydrous basalts, dacites and rhyolites. However, the viscosity of volatile-bearing melilititic melts, among the most plausible carriers of deep carbon, has not been investigated. In this study, we experimentally determined the viscosity of synthetic liquids with ~31 and ~39 wt% SiO₂, 1.60 and 1.42 wt% CO₂ and 5.7 and 1 wt% H₂O, respectively, at pressures from 1 to 4.7 GPa and temperatures between 1265 and 1755 °C, using the falling-sphere technique combined with in situ X-ray radiography. Our results show viscosities between 0.1044 and 2.1221 Pa·s, with a clear dependence on temperature and SiO₂ content. The atomic structure of both melt compositions was also determined at high pressure and temperature, using in situ multi-angle energy-dispersive X-ray diffraction supported by ex situ microFTIR and microRaman spectroscopic measurements. Our results yield evidence that the T–T and T–O (T = Si,Al) interatomic distances of ultrabasic melts are higher than those for basaltic melts known from similar recent studies. Based on our experimental data, melilititic melts are expected to migrate at a rate ~from 2 to 57 km·yr⁻¹ in the present-day or the Archaean mantle, respectively. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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21 pages, 3157 KiB

Open AccessArticle

Influence of Pre-Existing Nuclei on the Crystallization Kinetics of Primitive Alkaline Magmas: Insights on the Deep Feeding System of the Campi Flegrei Volcanic District

by Barbara Bonechi

Minerals 2020, 10(3), 234; https://doi.org/10.3390/min10030234 - 4 Mar 2020

Cited by 6 | Viewed by 2708

Abstract

Aiming to evaluate the influence of pre-existing nuclei on the clinopyroxene crystallization kinetics, time-series experiments were performed using both natural and vitrified starting materials. Experiments were carried out at pressure of 0.8 GPa, temperatures between 1220 and 1250 °C, and dwell times ranging from 0.16 to 12 h. Clinopyroxene growth rates of the runs performed using the natural starting material containing pre-existing nuclei (~2 × 10⁻⁷ to ~6 × 10⁻⁸ cm∙s⁻¹) are higher than those of the runs performed using the vitrified one (~3 × 10⁻⁷ to ~2 × 10⁻⁸ cm∙s⁻¹). In both cases the growth rates decrease with increasing time. Conversely, clinopyroxene nucleation rates are lower in the experiments performed using the natural powder (10² and 10 mm⁻³∙s⁻¹) compared to those performed with the glassy starting material (10⁵ and 10³ mm⁻³∙s⁻¹). The nucleation rates tend to decrease increasing dwell time in all the series up to ~3 h, after which it remains nearly constant. Finally, the combination of the obtained clinopyroxene growth rates with the crystal size analysis of natural clinopyroxenes, allowed to estimate the magma ascent rate and the recharge rate of the Campi Flegrei Volcanic District deep reservoir. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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12 pages, 4446 KiB

Open AccessArticle

A Study of Shock-Metamorphic Features of Feldspars from the Xiuyan Impact Crater

by Feng Yin and Deqiu Dai

Minerals 2020, 10(3), 231; https://doi.org/10.3390/min10030231 - 3 Mar 2020

Cited by 5 | Viewed by 5060

Abstract

Feldspar is the most abundant mineral in the Earth’s crust and is widely distributed in rocks. It is also one of the most common minerals in meteorites. Shock-metamorphic features in feldspar are widely used to calibrate the temperature and pressure of shock events and can also provide clues for searching for impact craters on Earth. In this study, shocked alkali feldspars in the lithic breccia and suevite from Xiuyan Impact Crater were investigated using polarizing optical microscopes, Raman spectroscopy and electron microprobes to better constrain the shock history of this crater. For this study, feldspar grains occurring in gneiss clasts in the impact breccia and four shock stages were identified, e.g., weakly shocked feldspar, moderately shocked feldspar, strongly shocked feldspar, and whole rock melting. According to the shock classification system for alkali feldspar and felsic rocks, we estimated the shock pressure (SP) and post-shock temperature (PST) histories of these gneiss clasts. Weakly shocked feldspars display irregular fractures and undulatory extinction, and their shock stage is F-S2, which indicates that SP and PST are from ~5 to ~14 GPa and ~100 °C, respectively. Moderately shocked feldspars show planar deformation features and are partially transformed into diaplectic glass, which indicates that the F-S5 shock stage of SP and PST is from ~32 to ~45 GPa and 300–900 °C. Strongly shocked feldspars that occur as vesicular glass indicate a shock stage of F-S6, and the SP and PST are 45–60 GPa and 900–1500 °C, respectively. The whole felsic rock melting occurs as mixed melt glass clast and belongs to the F-S7 stage, and SP and PST are >60 GPa and >1500 °C, respectively. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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20 pages, 13961 KiB

Open AccessArticle

Muscovite Dehydration Melting in Silica-Undersaturated Systems: A Case Study from Corundum-Bearing Anatectic Rocks in the Dabie Orogen

by Yang Li, Yang Yang, Yi-Can Liu, Chiara Groppo and Franco Rolfo

Minerals 2020, 10(3), 213; https://doi.org/10.3390/min10030213 - 27 Feb 2020

Cited by 9 | Viewed by 3790

Abstract

Corundum-bearing anatectic aluminous rocks are exposed in the deeply subducted North Dabie complex zone (NDZ), of Central China. The rocks consist of corundum, biotite, K-feldspar and plagioclase, and show clear macro- and micro-structural evidence of anatexis by dehydration melting of muscovite in the absence of quartz. Mineral textures and chemical data integrated with phase equilibria modeling, indicate that coarse-grained corundum in leucosome domains is a peritectic phase, reflecting dehydration melting of muscovite through the reaction: Muscovite = Corundum + K-feldspar + Melt. Aggregates of fine-grained, oriented, corundum grains intergrown with alkali feldspar in the mesosome domains are, instead, formed by the dehydration melting of muscovite with aluminosilicate, through the reaction: Muscovite + Al-silicate = Corundum + K-feldspar + Melt. P-T pseudosections modeling in the Na₂O-CaO-K₂O-FeO-MgO-Al₂O₃-SiO₂-H₂O-TiO₂ system constrains peak pressure-temperature (P-T) conditions at 900–950 °C, 9–14 kbar. The formation of peritectic corundum in the studied rocks is a robust petrographic evidence of white mica decompression melting that has occurred during the near-isothermal exhumation of the NDZ. Combined with P-T estimates for the other metamorphic rocks in the area, these new results further confirm that the NDZ experienced a long-lived high-T evolution with a near-isothermal decompression path from mantle depths to lower-crustal levels. Furthermore, our new data suggest that white mica decompression melting during exhumation of the NDZ was a long-lasting process occurring on a depth interval of more than 30 km. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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25 pages, 17658 KiB

Open AccessArticle

New Candidate Ultralow-Velocity Zone Locations from Highly Anomalous SPdKS Waveforms

by Michael S. Thorne, Surya Pachhai, Kuangdai Leng, June K. Wicks and Tarje Nissen-Meyer

Minerals 2020, 10(3), 211; https://doi.org/10.3390/min10030211 - 26 Feb 2020

Cited by 24 | Viewed by 4140

Abstract

Ultralow-velocity zones (ULVZs) at the core–mantle boundary (CMB) represent some of the most preternatural features in Earth’s mantle. These zones most likely contain partial melt, extremely high iron content ferropericlase, or combinations of both. We analyzed a new collection of 58,155 carefully processed and quality-controlled broadband recordings of the seismic phase SPdKS in the epicentral distance range from 106° to 115°. These data sample 56.9% of the CMB by surface area. From these recordings we searched for the most anomalous seismic waveforms that are indicative of ULVZ presence. We used a Bayesian approach to identify the regions of the CMB that have the highest probability of containing ULVZs, thereby identifying sixteen regions of interest. Of these regions, we corroborate well-known ULVZ existence beneath the South China Sea, southwest Pacific, the Samoa hotspot, the southwestern US/northern Mexico, and Iceland. We find good evidence for new ULVZs beneath North Africa, East Asia, and north of Papua New Guinea. We provide further evidence for ULVZs in regions where some evidence has been hinted at before beneath the Philippine Sea, the Pacific Northwest, and the Amazon Basin. Additional evidence is shown for potential ULVZs at the base of the Caroline, San Felix and Galapagos hotspots. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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15 pages, 2951 KiB

Open AccessArticle

Density of NaAlSi₂O₆ Melt at High Pressure and Temperature Measured by In-Situ X-ray Microtomography

by Man Xu, Zhicheng Jing, James A. Van Orman, Tony Yu and Yanbin Wang

Minerals 2020, 10(2), 161; https://doi.org/10.3390/min10020161 - 12 Feb 2020

Cited by 8 | Viewed by 3714

Abstract

In this study, the volumetric compression of jadeite (NaAlSi₂O₆) melt at high pressures was determined by three-dimensional volume imaging using the synchrotron-based X-ray microtomography technique in a rotation-anvil device. Combined with the sample mass, measured using a high-precision analytical balance prior to the high-pressure experiment, the density of jadeite melt was obtained at high pressures and high temperatures up to 4.8 GPa and 1955 K. The density data were fitted to a third-order Birch-Murnaghan equation of state, resulting in a best-fit isothermal bulk modulus

K_{T 0}

{10.8}_{- 5.3}^{+ 1.9}

GPa and its pressure derivative

K_{T 0}^{'}

{3.4}_{- 0.4}^{+ 6.6}

. Comparison with data for silicate melts of various compositions from the literature shows that alkali-rich, polymerized melts are generally more compressible than alkali-poor, depolymerized ones. The high compressibility of jadeite melt at high pressures implies that polymerized sodium aluminosilicate melts, if generated by low-degree partial melting of mantle peridotite at ~250–400 km depth in the deep upper mantle, are likely denser than surrounding mantle materials, and thus gravitationally stable. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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20 pages, 6015 KiB

Open AccessArticle

Two-Stage Origin of K-Enrichment in Ultrapotassic Magmatism Simulated by Melting of Experimentally Metasomatized Mantle

by Michael W. Förster, Stephan Buhre, Bo Xu, Dejan Prelević, Regina Mertz-Kraus and Stephen F. Foley

Minerals 2020, 10(1), 41; https://doi.org/10.3390/min10010041 - 31 Dec 2019

Cited by 30 | Viewed by 5900

Abstract

The generation of strongly potassic melts in the mantle requires the presence of phlogopite in the melting assemblage, while isotopic and trace element analyses of ultrapotassic rocks frequently indicate the involvement of subducted crustal lithologies in the source. However, phlogopite-free experiments that focus on melting of sedimentary rocks and subsequent hybridization with mantle rocks at pressures of 1–3 GPa have not successfully produced melts with K₂O >5 wt%–6 wt%, while ultrapotassic igneous rocks reach up to 12 wt% K₂O. Accordingly, a two-stage process that enriches K₂O and increases K/Na in intermediary assemblages in the source prior to ultrapotassic magmatism seems likely. Here, we simulate this two-stage formation of ultrapotassic magmas using an experimental approach that involves re-melting of parts of an experimental product in a second experiment. In the first stage, reaction experiments containing layered sediment and dunite produced a modally metasomatized reaction zone at the border of a depleted peridotite. For the second-stage experiment, the metasomatized dunite was separated from the residue of the sedimentary rock and transferred to a smaller capsule, and melts were produced with 8 wt%–8.5 wt% K₂O and K/Na of 6–7. This is the first time that extremely K-enriched ultrapotassic melts have been generated experimentally from sediments at low pressure applicable to a post-collisional setting. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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11 pages, 1828 KiB

Open AccessArticle

The High-Pressure Structural Evolution of Olivine along the Forsterite–Fayalite Join

by Martha G. Pamato, Fabrizio Nestola, Davide Novella, Joseph R. Smyth, Daria Pasqual, G. Diego Gatta, Matteo Alvaro and Luciano Secco

Minerals 2019, 9(12), 790; https://doi.org/10.3390/min9120790 - 14 Dec 2019

Cited by 12 | Viewed by 5061

Abstract

Structural refinements from single-crystal X-ray diffraction data are reported for olivine with a composition of Fo₁₀₀ (forsterite Mg₂SiO₄, synthetic), Fo₈₀ and Fo₆₂ (~Mg_1.6Fe_0.4SiO₄ and ~Mg_1.24Fe_0.76SiO₄, both natural) at room temperature and high pressure to ~8 GPa. The new results, along with data from the literature on Fo₀ (fayalite Fe₂SiO₄), were used to investigate the previously reported structural mechanisms which caused small variations of olivine bulk modulus with increasing Fe content. For all the investigated compositions, the M2 crystallographic site, with its bonding configuration and its larger polyhedral volume, was observed to control the compression mechanisms in olivine. From Fo₁₀₀ to Fo₀, the compression rates for M2–O and M1–O bond lengths were observed to control the relative polyhedral volumes, resulting in a less-compressible M1O₆ polyhedral volume, likely causing the slight increase in bulk modulus with increasing Fe content. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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18 pages, 6659 KiB

Open AccessArticle

High-Temperature Evolution of Point Defect Equilibria in Hydrous Forsterite Synthesized at 1100 °C and up to 4 GPa

by Alessandro Del Vecchio, Brent T. Poe, Valeria Misiti and Mariangela Cestelli Guidi

Minerals 2019, 9(10), 574; https://doi.org/10.3390/min9100574 - 20 Sep 2019

Cited by 3 | Viewed by 2948

Abstract

Water distribution in the deep Earth represents one of the most important topics in the field of geodynamics due to its large impact on the physical and chemical properties of the Earth’s mantle, such as electrical conductivity, seismic anisotropy, diffusion, and rheology. In this study, we synthesized hydrous forsterite at 1100 °C and up to 4 GPa with either a piston-cylinder or multianvil apparatus. As a starting material, we used synthetic forsterite, unbuffered by SiO₂, obtained by thermo-mechanical activation of talc and magnesium carbonate hydroxide. Hydration was carried out using liquid H₂O as hydrogen source. Samples were polycrystalline in an effort to distribute H₂O throughout the sample both rapidly and homogeneously. Using the Paterson calibration, we observed total water content concentrations ranging between 100 and 500 ppm wt H₂O. Multiple absorption bands are found in the frequency range between 3400 and 3650 cm⁻¹, identifying at least seven peaks in all samples. Vibrational bands were centered at 3476, 3535, 3550, 3566, 3578, 3605, and 3612 cm⁻¹, in good agreement with experimental studies conducted on both hydrous forsterite and single crystals of olivine. The stronger OH stretching peaks can be attributed to vibrational modes associated with the hydrogarnet defect

{4 H}_{Si}^{x}

in which four protons occupy a vacant tetrahedral site. None of the OH bands observed are found at frequencies associated with hydrogen occupying vacant octahedral sites. High-temperature FTIR spectroscopy was used to evaluate the evolution of IR spectra as a function of temperature, up to 500 °C. The complete reversibility of peak absorption vs. temperature in the OH stretching region confirms that no water loss occurred during heating. We observe an overall a decrease in total absorption with increasing temperature, and a prominent decrease in the relative intensities of the higher frequency bands (>3600 cm⁻¹) with respect to lower frequency bands. We have assigned a series of equilibrium expressions based on the variation of relative peak areas with temperature and find that enthalpies of these processes range between 0.047–0.068 eV (4.5–6.5 kJ/mol), very low in comparison to activation energies observed for electrical conduction in hydrous olivine. Major changes in the vibrational spectrum are expected to be related to configurational changes of the same fully protonated hydrogarnet defect species. However, the complexity of the FTIR spectra may also be related to partially protonated defects, such as the associate defect

{3 H}_{Si}^{'}

H_{i}^{•}

generated by a dissociation reaction of the hydrogarnet species. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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17 pages, 33360 KiB

Open AccessArticle

High-Temperature Mineral Phases Generated in Natural Clinkers by Spontaneous Combustion of Coal

by Elisa Laita, Blanca Bauluz and Alfonso Yuste

Minerals 2019, 9(4), 213; https://doi.org/10.3390/min9040213 - 1 Apr 2019

Cited by 14 | Viewed by 5459

Abstract

The aim of this study is to analyze natural clinkers (= calcined clays by coal combustion) from a lower Cretaceous coal outcrop in Ariño (Teruel, NE Spain) in order to describe mineral and textural transformations produced during the spontaneous combustion of coal. To achieve this aim, samples were analyzed using X-ray diffraction and optical and electron microscopy. Spontaneous combustion resulted in the melting of the surrounding clays, with the generation of an Al–Si-rich vitreous phase. Subsequently, high-temperature phases crystallized from this vitreous phase. These new minerals are interesting due to their similarity with those formed during ceramic processes, used in the manufacture of stoneware and ceramic tiles, as well as in refractory ceramics, and with natural events such as metamorphic and igneous processes. The studied natural clinkers are composed of vitreous phase mullite, hematite, hercynite, cristobalite, quartz, pyroxenes, cordierite, gypsum, pyrite, and calcium oxides. A trend from hematite to hercynite composition indicates compositional variations at sample scale, which evidence d-spacing differences in hercynite and may be related to the Al and Fe content in hercynite depending on its texture. The mullite shows higher Si/Al ratio (1.21) than the theoretical composition (0.35), indicating that this mullite is more Si-rich. Three pyroxene-type compositions (diopside-type, ferrosilite-type, and a Ca–Al-rich pyroxene) were found. Both the mullite and the pyroxenes are nonstoichiometric. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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10 pages, 2553 KiB

Open AccessArticle

Electrical Conductivity of Fluorite and Fluorine Conduction

by Hanyong Liu, Qiao Zhu and Xiaozhi Yang

Minerals 2019, 9(2), 72; https://doi.org/10.3390/min9020072 - 27 Jan 2019

Cited by 7 | Viewed by 7271

Abstract

Fluorine is a species commonly present in many minerals in the Earth’s interior, with a concentration ranging from a few ppm to more than 10 wt. %. Recent experimental studies on fluorine-bearing silicate minerals have proposed that fluorine might be an important charge carrier for electrical conduction of Earth materials at elevated conditions, but the results are somewhat ambiguous. In this investigation, the electrical conductivity of gem-quality natural single crystal fluorite, a simple bi-elemental (Ca and F) mineral, has been determined at 1 GPa and 200–650 °C in two replication runs, by a Solartron-1260 Impedance/Gain Phase analyzer in an end-loaded piston-cylinder apparatus. The sample composition remained unchanged after the runs. The conductivity data are reproducible between different runs and between heating-cooling cycles of each run. The conductivity (σ) increases with increasing temperature, and can be described by the Arrhenius law, σ = 10^(5.34 ± 0.07)·exp[−(130 ± 1, kJ/mol)/(RT)], where R is the gas constant and T is the temperature. According to the equation, the conductivity reaches ~0.01 S/m at 650 °C. This elevated conductivity is strong evidence that fluorine is important in charge transport. The simple construction of this mineral indicates that the electrical conduction is dominated by fluoride (F⁻). Therefore, fluorine is potentially an important charge carrier in influencing the electrical property of Fluorine-bearing Earth materials. Full article

(This article belongs to the Special Issue Properties of Melt and Minerals at High Pressures and High Temperatures)

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