Next Article in Journal
Petrographical and Geochemical Signatures Linked to Fe/Mn Reduction in Subsurface Marine Sediments from the Hydrate-Bearing Area, Dongsha, the South China Sea
Previous Article in Journal
Geochronological Study of the Jiashengpan Zn–Pb Deposit in Northern China: Implications for Base Metal Mineralization in Collisional Orogens
Previous Article in Special Issue
Editorial for the Special Issue “Platinum-Group Minerals: New Results and Advances in PGE Mineralogy in Various Ni-Cu-Cr-PGE Ore Systems”
Open AccessArticle

Factors Controlling the Gallium Preference in High-Al Chromitites

Department of Chemistry, University of Crete, Heraklion GR-70013, Crete, Greece
Author to whom correspondence should be addressed.
Minerals 2019, 9(10), 623;
Received: 6 August 2019 / Revised: 26 September 2019 / Accepted: 7 October 2019 / Published: 10 October 2019
Gallium (Ga) belongs to the group of critical metals and is of noticeable research interest. Although Ga3+ is highly compatible in high-Al spinels a convincing explanation of the positive Ga3+–Al3+ correlation has not yet been proposed. In the present study, spinel-chemistry and geochemical data of high-Al and high-Cr chromitites from Greece, Bulgaria and the Kempirsai Massif (Urals) reveals a strong negative correlation (R ranges from −0.95 to −0.98) between Cr/(Cr + Al) ratio and Ga in large chromite deposits, suggesting that Ga hasn’t been affected by re-equilibration processes. In contrast, chromite occurrences of Pindos and Rhodope massifs show depletion in Ga and Al and elevated Mn, Co, Zn and Fe contents, resulting in changes (sub-solidus reactions), during the evolution of ophiolites. Application of literature experimental data shows an abrupt increase of the inversion parameter (x) of spinels at high temperature, in which the highest values correspond to low-Cr3+ samples. Therefore, key factors controlling the preference of Ga3+ in high-Al chromitites may be the composition of the parent magma, temperature, redox conditions, the disorder degree of spinels and the ability of Al3+ to occupy both octahedral and tetrahedral sites. In contrast, the competing Cr3+ can occupy only octahedral sites (due to its electronic configuration) and the Ga3+ shows a strong preference on tetrahedral sites. View Full-Text
Keywords: chromite; gallium; spinel; structure; composition; correlation; ophiolites; disorder chromite; gallium; spinel; structure; composition; correlation; ophiolites; disorder
Show Figures

Figure 1

MDPI and ACS Style

Eliopoulos, I.-P.D.; Eliopoulos, G.D. Factors Controlling the Gallium Preference in High-Al Chromitites. Minerals 2019, 9, 623.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop