Ammonium-Bearing Fluorapophyllite-(K) in the Magnesian Skarns from Aleului Valley, Pietroasa, Romania

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dc.citation.articleNumber1362en_US
dc.citation.issueNumber11en_US
dc.citation.journalTitleMineralsen_US
dc.citation.volumeNumber13en_US
dc.contributor.authorMarincea, Ştefanen_US
dc.contributor.authorDumitraş, Delia-Georgetaen_US
dc.contributor.authorSava Ghineţ, Cristinaen_US
dc.contributor.authorFiliuţă, Andra Elenaen_US
dc.contributor.authorDal Bo, Fabriceen_US
dc.contributor.authorHatert, Frédéricen_US
dc.contributor.authorCostin, Geluen_US
dc.date.accessioned2024-05-03T15:51:12Zen_US
dc.date.available2024-05-03T15:51:12Zen_US
dc.date.issued2023en_US
dc.description.abstractAn ammonium-bearing fluorapophyllite-(K) occurs as a late hydrothermal product in the outer endoskarn zone from Aleului Valley (N 46°37′04″, E 22°35′22″), located at the contact of the granodiorite laccolith from Pietroasa, of Upper Cretaceous age, with Anisian dolostones. Associated minerals are wollastonite, K feldspar, diopside, fluorapatite, talc, and pectolite. The chemical structural formula is [K0.985Na0.012(NH4)0.076]Σ=1.073(Ca4.009Mn0.001Fe2+0.003Mg0.002Ba0.001)Σ=4.016(Si7.953Al0.047) O20.029[F0.899(OH)0.101]·8.059H2O. The structure was successfully refined as tetragonal, space group P4/mnc, with cell parameters of a = 8.9685(1) Å and c = 15.7885(5) Å. The indices of refraction are ω = 1.534(1) and ε = 1.536(1). The calculated density is Dx = 2.381 g/cm3, in good agreement with the measured density, Dm = 2.379(4) g/cm3. The thermal analysis shows that the mineral completely dehydrates at up to 450 °C (endothermic effects at 330, 371, and 448 °C) and loses ammonium at 634 °C. In the infrared spectra, the multiplicity of the bands assumed to be silicate modes (1ν1 + 3ν3 + 2ν2 + 3ν4) agrees with the reduction in the symmetry of the SiO44− ion from Td to Cδ. Fluorapophyllite-(K) from Aleului Valley is of late hydrothermal origin and crystallized from F-rich fluids originating from the granodiorite intrusion, which mobilized K, Ca, and Si from the pre-existing feldspar.en_US
dc.identifier.citationMarincea, Ş., Dumitraş, D.-G., Sava Ghineţ, C., Filiuţă, A. E., Dal Bo, F., Hatert, F., & Costin, G. (2023). Ammonium-Bearing Fluorapophyllite-(K) in the Magnesian Skarns from Aleului Valley, Pietroasa, Romania. Minerals, 13(11), Article 11. https://doi.org/10.3390/min13111362en_US
dc.identifier.digitalminerals-13-01362-v2en_US
dc.identifier.doihttps://doi.org/10.3390/min13111362en_US
dc.identifier.urihttps://hdl.handle.net/1911/115567en_US
dc.language.isoengen_US
dc.publisherMDPIen_US
dc.rightsExcept where otherwise noted, this work is licensed under a Creative Commons Attribution (CC BY) license. Permission to reuse, publish, or reproduce the work beyond the terms of the license or beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_US
dc.titleAmmonium-Bearing Fluorapophyllite-(K) in the Magnesian Skarns from Aleului Valley, Pietroasa, Romaniaen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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