Indium-Carrier Minerals in Polymetallic Sulphide Ore Deposits: A Crystal Chemical Insight into an Indium Binding State Supported by X-ray Absorption Spectroscopy Data

Abstract

Indium is a typical chalcophile element of the Earth's crust, with a very low average content that seldom forms specific minerals, occurring mainly as dispersed in polymetallic sulphides. Indium recovery is based primarily on zinc extraction from sphalerite, the prototype of so-called tetrahedral sulphides, wherein metal ions fill half of the available tetrahedral sites within the cubic closest packing of sulphur anions, leaving interstices accessible for further in-filling. Ascertaining the tendency towards the establishment of In-In interactions through an x-ray absorption spectroscopy approach would efficiently contribute to understanding the behavior of indium in the carrier mineral. The successful results of applying such a near-edge absorption (XANES) study at In L 3 -edge to samples collected at the Lagoa Salgada polymetallic orebody in the Iberian Pyrite Belt (IPB) are described and the crystal chemistry of indium is re-evaluated, disclosing a potential clue for the metal binding state in polymetallic sulphides.

Trap Passivation in Indium-Based Quantum Dots through Surface Fluorination: Mechanism and Applications

“…A blue shift of In 3d XPS peaks toward the same peak from InF 3 after the HF treatment also supports the reaction of In with HF (Figure 2(b) and Table 1). This is consistent with the blue shift (3 eV) of the In L 3 -absorption edge at ∼3740 eV and the sharpening of the white line at ∼3735 eV in the X-ray absorption near edge structure (XANES) 42 ( Figure S5 in the SI). On the other hand, the formation of P−F bonds would be improbable, since the positions of the P 2p peak around 129 eV associated with phosphide are almost constant regardless of the HF treatment and quite different from the P 2p peak from TMAPF 6 at 136.5 eV in Figure 2 are detected, not those corresponding to PF, PF 2 , and PF 3 ( Figure S6 in the SI).…”

“…A blue shift of In 3d XPS peaks toward the same peak from InF 3 after the HF treatment also supports the reaction of In with HF (Figure 2(b) and Table 1). This is consistent with the blue shift (3 eV) of the In L 3 -absorption edge at ∼3740 eV and the sharpening of the white line at ∼3735 eV in the X-ray absorption near edge structure (XANES) 42 (Figure S5 1). In brief, the HF treatment on InP QDs makes new chemical bonds of the surface indium with fluorine accompanied by the detachment of the organic carboxylate ligands and hydroxides originally bound on the surface indium.…”

“…If the red shift of 0.08 eV originates from the increase of QD sizes, the size change should be about 0.3−0.4 nm. 42 However, almost constant QD sizes before and after the HF treatment obtained from scanning transmission electron microscope images suggest that the change of the absorption edge might not result from the simple morphological change ( Figure S2 in the SI). To understand this new HF treatment regime, we varied the experimental conditions for the HF treatment and found two parameters that control the peak shifts.…”

“…Additional red shifts and PLQY improvement to 45% in samples stored for 1 month under ambient conditions corroborate that there was negligible etching despite the significant PLQY enhancement. If the red shift of 0.08 eV originates from the increase of QD sizes, the size change should be about 0.3–0.4 nm . However, almost constant QD sizes before and after the HF treatment obtained from scanning transmission electron microscope images suggest that the change of the absorption edge might not result from the simple morphological change (Figure S2 in the SI).…”

Distribution of In and other rare metals in cassiterite and associated minerals in Sn ± W ore deposits of the western Variscan Belt

“…The major In-rich deposits are, by decreasing order of importance, sediment-hosted massive sulfides, volcanogenic massive sulfides (VMS), skarn, epithermal, and porphyry; sediment-hosted Pb-Zn and VMS represent more than 60% of In resources (Werner et al, 2017). Magmatic-hydrothermal mineralizations mostly associated with post-collisional magmatic pulses, including skarn-, greisen-, and vein-type mineralization, also represent promising exploration targets for In (SE Finland; Erzgebirge/Kru sné Hory; Far East Russia; SW England; South China Tin Belt) (Seifert, 2008; The Variscan Belt contains several ore deposits identified for their significant In resources (Werner et al, 2017), including VMS in Portugal such as Neves Corvo (Pinto et al, 2014) or Lagoa Salgada (Figueiredo et al, 2012), different ore-deposit types in the Erzgebirge, eastern Germany (skarn-type ores in the Pöhla district: Schuppan & Hiller, 2012;Bauer et al, 2017;Jeske & Seifert, 2017), polymetallic Sn(-Ag)-base metal vein-and greisen-type deposits in the old Freiberg, Marienberg, Annaberg, and Ehrenfriederdorf-Geyer mining districts (Seifert et al, 1992;Jung & Seifert, 1996;Seifert & Sandmann, 2006;Seifert, 2015) and Sn deposits in SW England (Andersen et al, 2016). According to these recent investigations, late-Variscan granite-related Sn mineralizations might also represent potential interesting In targets.…”