Mineralogical Distribution of Germanium, Gallium and Indium at the Mt Carlton High-Sulfidation Epithermal Deposit, NE Australia, and Comparison with Similar Deposits Worldwide

Abstract

Germanium, gallium and indium are in high demand due to their growing usage in high-tech and green-tech applications. However, the mineralogy and the mechanisms of concentration of these critical elements in different types of hydrothermal ore deposits remain poorly constrained. We investigated the mineralogical distribution of Ge, Ga and In at the Mt Carlton high-sulfidation epithermal deposit in NE Australia, using electron probe microanalysis and laser ablation inductively-coupled plasma mass spectrometry. Parageneses from which selected minerals were analyzed include: Stage 1 acid sulfate alteration (alunite), Stage 2A high-sulfidation enargite mineralization (enargite, argyrodite, sphalerite, pyrite, barite), Stage 2B intermediate-sulfidation sphalerite mineralization (sphalerite, pyrite, galena) and Stage 3 hydrothermal void fill (dickite). Moderate to locally high concentrations of Ga were measured in Stage 1 alunite (up to 339 ppm) and in Stage 3 dickite (up to 150 ppm). The Stage 2A ores show enrichment in Ge, which is primarily associated with argyrodite (up to 6.95 wt % Ge) and Ge-bearing enargite (up to 2189 ppm Ge). Co-existing sphalerite has comparatively low Ge content (up to 143 ppm), while Ga (up to 1181 ppm) and In (up to 571 ppm) are higher. Sphalerite in Stage 2B contains up to 611 ppm Ge, 2829 ppm Ga and 2169 ppm In, and locally exhibits fine colloform bands of an uncharacterized Zn-In mineral with compositions close to CuZn 2 (In,Ga)S 4 . Barite, pyrite and galena which occur in association with Stage 2 mineralization were found to play negligible roles as carriers of Ge, Ga and In at Mt Carlton. Analyzed reference samples of enargite from seven similar deposits worldwide have average Ge concentrations ranging from 12 to 717 ppm (maximum 2679 ppm). The deposits from which samples showed high enrichment in critical elements in this study are all hosted in stratigraphic sequences that locally contain carbonaceous sedimentary rocks. In addition to magmatic-hydrothermal processes, such rocks could potentially be important for the concentration of critical elements in high-sulfidation epithermal deposits.

Trace Element Distributions in the Zn-Pb (Mississippi Valley-Type) and Cu-Ag (Kupferschiefer) Sediment-Hosted Deposits in Poland

“…Silver concentrations in sphalerite range from below detection limit to 3310 ppm (arithmetic mean 219 ppm and n = 500) ( Figure 15C) and Cu concentrations up to 10,470 ppm. Indium was detected only in a few sphalerite crystals (maximum 290 ppm), although it is reported as a trace component within sphalerite in many MVT-type world deposits [71][72][73][74][75][76]. According to previous studies, the ranges in concentrations of minor and trace elements in any ore minerals vary widely throughout the district as well as in the specific mines [28,29].…”

The Poopó Polymetallic Epithermal Deposit, Bolivia: Mineralogy, Genetic Constraints, and Distribution of Critical Elements

“…As of EPMA analyses, relevant indium contents were found in franckeite, rhodostannite, sphalerite, cassiterite and stannite, but only traces of gallium were found. EPMA values and guidelines from References [29][30][31][32][33] allowed to selecting the most susceptible minerals to contain relevant amounts of strategic elements indium and gallium, which were considered to be sphalerite, cassiterite, stannite and rhodostannite. The most noticeable germanium contents were consistently obtained by means of EPMA in rhodostannite (up to 0.21 wt.% Ge) and franckeite (up to 0.16 wt.% Ge), and this element was also quantified in bismuthinite, terrywallaceite, jamesonite, stannite, treasurite, and in unidentified minerals (Table S1).…”

Indium Mineralization in the Volcanic Dome-Hosted Ánimas–Chocaya–Siete Suyos Polymetallic Deposit, Potosí, Bolivia

“…The occurrence of In is reported in ore deposits that span a broad range of ages and mineralization styles [11,14]. High concentrations are described prominently in exhalative deposits hosted in volcanic (e.g., [22,23]) and sedimentary sequences (e.g., [24]), granite-hosted (including greisen-type, e.g., [25,26]), vein-stockwork Sn-W, porphyry Sn and xenothermal Sn-W-Cu-Zn-Pb-Ag veins (e.g., [27][28][29][30]), skarn (e.g., [18,31]), ,and epithermal (e.g., [15,16,32,33]) deposits.…”