Dellagiustaite: A Novel Natural Spinel Containing V2+

Minerals

Sarah E.M. Gain¹  William L. Griffin¹  Renato Pagano²  Adriana Pagano²  Fernando Cámara³  Luca Bindi⁴ 

[1] Australian Research Council Centre of Excellence for Core to Crust Fluid Systems (CCFS)/GEMOC, Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia;Casella Postale 37, Cinisello, Milano, Italy;Dipartimento di Scienze della Terra 'A. Desio', Università degli Studi di Milano, Via Luigi Mangiagalli 34, 20133 Milano, Italy;Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira 4, I-50121 Firenze, Italy;

关键词: dellagiustaite;    spinel supergroup;    oxyspinel subgroup;    new mineral species;    crystal structure;    Sierra de Comechingones;    Argentina;    Mt Carmel;    Israel;   

DOI  :  10.3390/min9010004

来源: DOAJ

【 摘 要 】

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 (Al1.09V2+0.91V3+0.87Mg0.08Ti3+0.04Mn0.01)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 = 1.782(2) Å and = 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 as TAlM( V0.912+ V0.883+ Al0.093+ Mg0.08 Ti0.033+Mn0.01)O4.

【 授权许可】

Unknown