Dellagiustaite, ideally Al2V2+O4, is a new spinel-group mineral from Sierra de Comechingones, San Luis, Argentina, where it is found associated with hibonite (containing tubular inclusions, 5–100 µm, of metallic vanadium), grossite, and two other unknown phases with ideal stoichiometry of Ca2Al3O6F and Ca2Al2SiO7. A very similar rock containing dellagiustaite has been found at Mt Carmel (northern Israel), where super-reduced mineral assemblages have crystallized from high-T melts trapped in corundum aggregates (micro-xenoliths) within picritic-tholeiitic lavas ejected from Cretaceous volcanoes. In the holotype, euhedral grains of dellagiustaite are found as inclusions in grossite. The empirical average chemical formula of dellagiustaite is (Al1.09 V2+ 0.91 V3+ 0.87 Mg0.08 Ti3+ 0.04 Mn0.01)Σ3O4, but it may show limited replacement of V2+ by Mg and of V3+ by Al. As Al is the dominant trivalent cation, the ideal formula is Al2V2+O4 according to the current IMA rules. Dellagiustaite shows the usual space group of spinel-group minerals (Fd3m, R1 = 1.46%) with a = 8.1950(1) Å. The observed mean bond lengths <T–O> = 1.782(2) Å and <M–O> = 2.0445(9) Å, the observed site scattering (T = 13.3 eps, M = 22.5 eps), and the chemical composition show that dellagiustaite is an inverse spinel: T tetrahedra are occupied by Al3+, whereas M octahedra are occupied by V2+ and V3+, leading to the site assignment asTAlM(V2+ 0.91 V3+ 0.88 Al3+ 0.09 Mg0.08 Ti3+ 0.03 Mn0.01)O4. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.
Dellagiustaite: A Novel Natural Spinel Containing V2+ / F. Cámara, L. Bindi, A. Pagano, R. Pagano, S.E.M. Gain, W.L. Griffin. - In: MINERALS. - ISSN 2075-163X. - 9:1(2019 Jan 01).
|Titolo:||Dellagiustaite: A Novel Natural Spinel Containing V2+|
CAMARA ARTIGAS, FERNANDO (Primo) [Writing – Original Draft Preparation] (Corresponding)
|Parole Chiave:||Argentina; Dellagiustaite; Israel; Mt carmel; New crystal structure; Oxyspinel subgroup; Sierra de comechingones; Spinel supergroup|
|Settore Scientifico Disciplinare:||Settore GEO/06 - Mineralogia|
|Progetto:||PIANO DI SOSTEGNO ALLA RICERCA 2015-2017 - LINEA 2 "DOTAZIONE ANNUALE PER ATTIVITA' ISTITUZIONALE"|
|Data di pubblicazione:||1-gen-2019|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.3390/min9010004|
|Appare nelle tipologie:||01 - Articolo su periodico|