OxyEMG: an application for determination of the oxyspinel group end-members based on electron microprobe analyses

• Published in: European journal of mineralogy (Stuttgart) 2024-01, Vol.36 (1), p.87-98
• Main Authors: Ferracutti, Gabriela R., Asiain, Lucía M., Antonini, Antonella S., Tanzola, Juan E., Ganuza, M. Luján
• Format: Article
• Language: English
• Subjects: Cations; Chemical elements; Chromite; Composition; Electron probe microanalysis; Electron probes; Hausmannite; Hercynite; Intermetallic compounds; Iron compounds; Magnetite; Manganese; Mathematical analysis; Mineralogical research; Nickel aluminides; Nickel base alloys; Nickel compounds; Prisms; Properties; Solid solutions; Spinel group; Testing
• ISSN: 1617-4011; 0935-1221; 1617-4011
• DOI: 10.5194/ejm-36-87-2024

The Oxyspinel group End-Member Generator (OxyEMG) is an improved version of the EMG application. This new version allows for calculating, based on electron microprobe analysis (EMPA), the proportions of 31 end-member components in an oxyspinel composition. These components are MgAl2O4 (spinel), FeAl2O4 (hercynite), MnAl2O4 (galaxite), ZnAl2O4 (gahnite), NiAl2O4 (chihmingite), CuAl2O4 (thermaerogenite), MgFe2O4 (magnesioferrite), Fe3O4 (magnetite), MnFe2O4 (jacobsite), ZnFe2O4 (franklinite), NiFe2O4 (trevorite), CuFe2O4 (cuprospinel), FeMn2O4, MgMn2O4, Mn3O4 (hausmannite), ZnMn2O4 (hetaerolite), MgCr2O4 (magnesiochromite), FeCr2O4 (chromite), MnCr2O4 (manganochromite), ZnCr2O4 (zincochromite), NiCr2O4 (nichromite), CoCr2O4 (cochromite), MgV2O4 (magnesiocoulsonite), FeV2O4 (coulsonite), MnV2O4 (vuorelainenite), Co3O4 (guite), TiMg2O4 (qandilite), TiFe2O4 (ulvöspinel), SiMg2O4 (ringwoodite), SiFe2O4 (ahrensite) and GeFe2O4 (brunogeierite). Compared with the older version, OxyEMG allows for (a) calculating 12 additional oxyspinel group end-member compositions (chihmingite, thermaerogenite, hausmannite, hetaerolite, FeMn2O4, MgMn2O4, cuprospinel, cochromite, guite, ringwoodite, ahrensite and brunogeierite), (b) discriminating the cation valency not only for Fe2+–Fe3+ but also for Mn2+–Mn3+ and Co2+–Co3+, and (c) changing the method to calculate the components of the magnetite and ulvöspinel prisms. As in EMG, this new version is an application that does not require an installation process and was created with the purpose of performing calculations to obtain cation proportions (per formula unit, p.f.u.), end-members of the oxyspinel group, a ΣR3+ value, a ΣR2+ value, ΣR3+ / ΣR2+ ratios, redistribution proportions for the corresponding end-members in the magnetite or ulvöspinel prisms, and a data validation section to check the results.