The role of Fe2+ and Fe3+ in synthetic Fe-substituted tetrahedrite

Makovicky, Emil; Forcher, Karl; Lottermoser, Werner; Amthauer, Georg

doi:10.1007/bf01164223

Cited by 66 publications

(63 citation statements)

References 11 publications

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“…The existence of metal-poor samples (metal sum less than 12 apfu), reported in Table 2, supports the hypothesis of the presence of Cu 2+ or Fe 3+ , or both, as suggested by Foit & Ulbricht (2001). In these metal-poor samples, the possible presence of Fe 3+ does not seem to be correlated with the total Fe content, as reported by Makovicky et al (1991).…”

Section: Chemical Compositionsupporting

confidence: 68%

Crystal Chemistry of Tetrahedrite Solid-Solution: Epr and Magnetic Investigations

Benedetto

Bernardini

Borrini

et al. 2002

The Canadian Mineralogist

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One hundred and thirty samples from the collection of the Natural History Museum in Florence, labeled as tetrahedrite, have been extensively studied by means of SEM, XRD, EPMA, DTA, EPR and SQUID techniques. Wide-ranging substitutions, confirmed by compositional data, play a fundamental role in the thermal behavior, "stabilizing" natural tetrahedrite with respect to the synthetic equivalent. In order to determine the valence state and site occupancies of Cu and Fe, electron paramagnetic resonance (EPR) and magnetic measurements were performed on selected samples of natural tetrahedrite. EPR measurements were performed down to 130 K, and magnetic susceptibility measurements, in the range 2-300 K. EPR magnetic parameters were determined on the basis of spectral simulations. The behaviour of --1 versus temperature was interpreted by means of Heisenberg's model, thus yielding values for the Curie and Weiss constants. All samples are characterized by the presence of small amounts of Cu 2+ and Fe 2+ ; Fe 3+ was detected only in metal-deficient samples. Both Cu and Fe occupy the tetrahedral site; whereas in some samples the former appears aggregated in dimers, the latter is randomly distributed over the lattice. The results of the study confirm the crystal-chemical formula of the tetrahedrite samples investigated.Keywords: tetrahedrite solid-solution, compositional data, thermal behavior, electron paramagnetic resonance, magnetic susceptibility, crystal chemistry, cupric ion. SOMMAIRENous avons caractérisé cent-trente échantillons appelés tétraédrite dans la collection du Musée d'Histoire Naturelle à Florence par microscopie électronique par balayage, diffraction X, analyse par microsonde électronique, analyse thermique différentielle, résonance paramagnétique des électrons, et la technique SQUID. Des substitutions d'étendue importante, confirmées par données chimiques, exercent un rôle fondamental dans le comportement thermique, "stabilisant" la tétraédrite naturelle par rapport à l'équivalent synthétique. Afin de déterminer la valence et la position de Cu et Fe, nous avons déterminé la résonance paramagnétique des électrons (RPE) d'échantillons naturels choisis jusqu'à 130 K, et les propriétés magnétiques sur l'intervalle 2-300 K. Les paramètres magnétiques des spectres RPE ont été déterminés par simulation. Le comportement de --1 en fonction de la température a été interpreté au moyen du modèle de Heisenberg, menant ainsi à une évaluation des constantes de Curie et de Weiss. Tous les échantillons contiennent de faibles quantités de Cu 2+ et de Fe 2+ . En revanche, on a décelé le Fe 3+ seulement dans les échantillons déficitaires en métaux. Le Cu et le Fe occupent le site tétraédrique. Tandis que le Cu semble agencé en dimères, le Fe serait plutôt distribué de façon aléatoire dans le réseau. Les résultats de notre étude confirment la formule cristallochimique des échantillons de tétraédrite étudiés. (Traduit par la Rédaction)Mots-clés: solution solide de la tétraédrite, données sur la composition, comportemen...

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Section: Chemical Compositionsupporting

confidence: 68%

Crystal Chemistry of Tetrahedrite Solid-Solution: Epr and Magnetic Investigations

Benedetto

Bernardini

Borrini

et al. 2002

The Canadian Mineralogist

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“…Fe 3 +; --= percentage of Fe 3 + relative to total iron. Analytical conditions are as reported in Table 6 deviations: (Cu, Ag) > 10 and (Fe, Zn) < 2, due to substitutions: 2(Cu, Ag) + = (Fe, Zn) z+ and Cu 2+ = (Fe, Zn) 2+ (Wuensch 1964;Charlat and L6vy 1974;Springer 1969;Peterson and Miller 1986;Chikhaoui 1981;Johnson et al 1987;O'Leary and Sack 1987;Johnson et al 1988;Charnock et al 1989;Mackovicky et al 1990). As noted by Johnson et al (1988), substitutions of elements inside individual brackets, are nearly ideal except for Cu-Ag and As-Sb.…”

Section: Copper Complex Sulfidesmentioning

confidence: 98%

“…The complete natural field of the tennantite-tetrahedrite solid solution, stretches from Culz(As, SbhSx3 toward Cuxo(Fe, Znh(As, SbhS13 (Vaughan and Pattrick 1984;O'Leary and Sack 1987;Charnock et al 1989;Mackovicky et al 1990 and references cited). In minerals of these series with Cu > 1 p.f.u, and with Fe < 1 p.f.u., Cu is formally divalent and iron occurs as Fe 3 +, until the composition Cu+IFe3+Sb4S13 is reached (Hall et al 1974;Charnock et al 1989;Mackovicky et al 1990). From this composition a gradual conversion of Fe 3 § into Fe 2+ begins until the final fully-substituted composition is reached (Mackovicky et al 1990).…”

Section: Copper Complex Sulfidesmentioning

confidence: 98%

“…These minerals would have deposited contemporaneously, early in Stage 3, whereas tennantite I with higher Sb (Table 7), might have formed later, presumably at the end of this stage. During the last decades, much progress has been made toward understanding the crystal structure and chemistry of both the synthetic (Pauling and Neuman 1934;Wuensch 1964;Wuensch et al 1966;Hall 1972;Mackovicky and Skinner 1978;Johnson et al 1987Johnson et al , 1988Charnock et al 1989;Mackovicky et al 1990) and the natural (Charlat and L6vy 1974;Hall et al 1974;O'Leary and Sack 1987;Peterson and Miller 1986;Charnock et al 1989) tetrahedrite-tennantite series. The ideal structure (1/2 unit cell) of these series (see Johnson et al 1988 and M2 = Cu, Ag and Fe (Charnock et al 1989;Mackovicky et al 1990).…”

Section: Copper Complex Sulfidesmentioning

confidence: 98%

“…In natural and low temperature members (see Mackovicky and Skinner 1978;Mackovicky et al 1990) of the tennantite-tetrahedrite series frequently associated with polymetallic sulfide base-metal deposits, Cu, Ag, Zn, Fe, Zn, Mn, and Cd (and Hg e.g., Oued el Maden, Tunisia; Slim-Shimi 1992), we find quantitatively the most important metals to be incorporated, yielding the ideal stoichiometry: (Cu, Ag) 1 o(Zn, Fe)2(As, Sb)4S 13 with Structural formula calculated on the basis of(Cu + Ag + Zn + Fe) = 12 p.f.u. Fe 3 +; --= percentage of Fe 3 + relative to total iron.…”

Section: Copper Complex Sulfidesmentioning

confidence: 99%

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Sulfide geochemistry and genesis of Chouichia and Ain el Bey copper deposits in northwestern Tunisia

et al. 1996

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Abstract. The Chouichia and Ain el Bey copper veins thatoccur in the Eastern Atlas fold belt in northwestern Tunisia, are hosted in Upper Cretaceous-Paleogene sedimentary sequences in a regional transcurrent shear zone. Paragenetic assemblages were formed during four distinct stages all of which are separated by fracturing and brecciation: Stage 1 consists of low temperature siderite (160-180 :'C) formation in association with pyrite, including framboidal pyrite and marcasite. Stage 2 includes pseudomorphing of marcasite by As-rich pyrite and arsenopyrite, and formation of chalcopyrite at higher temperatures (200-300 C) from S-rich, Fe-Cu-bearing fluids; As contents in individual pyrite and arsenopyrite crystals increase markedly in the rims relative to the centers, thus indicating non-equilibrium conditions. Stage 3 involves fracturing and brecciation predating deposition of enargite, luzonite and tennantite at Ain el Bey, and famatinite and tetrahedrite at Chouichia, from As-Sb-Bi-bearing oreforming fluids; tennantite-tetrahedrite series exhibit iron and copper-excess replacements in tetrahedral sites interrelated with Cu-Fe interactions (electron transfer). In Stage 4 fracturing was followed by calcite formation in voids. Comprehensive data was obtained from scanning electron microprobe (SEM) and microprobe chemical analyses of minerals, geothermometry using sulfur isotopes, As contents in arsenopyrite crystals and fluid inclusions in siderite and calcite, support an input of magmatic hydrothermal ore-forming fluids, although contamination by sedimentary sulfur were also identified.

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High Performance Thermoelectricity in Earth‐Abundant Compounds Based on Natural Mineral Tetrahedrites

Morelli

Xia

et al. 2012

Advanced Energy Materials

495

560

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Materials and Methods Tetrahedrite synthesis: Cu 12-x (Fe,Zn) 2-x Sb 4 S 13 samples were synthesized by direct reaction of the starting elements-Cu(99.99 %, Alfa-Aesar), Sb(99.9999 %, Alfa-Aesar), and S, Zn, Fe (99.999%, Alfa-Aesar). The elements were weighed out in stoichiometric proportions using a high-precision Mettler balance; typical charges were on the order of 5 grams total, with individual element masses weighed out with an accuracy of 0.0005 g (0.5 mg). The stoichiometric proportions of the elements were placed into quartz ampoules of inside diameter 10 mm and wall thickness 0.5 mm. The ampoules were evacuated of air using a turbo molecular pump; typical final pressures were <10-5 Torr. The ampoules were sealed under dynamic vacuum using an oxygen/methane torch and provided with a small quartz hook on the top. A wire was attached to this hook and the ampoules were suspended in a vertical Thermolyne tube furnace at room temperature. The furnace was heated at 0.3 ºC min-1 to 650 ºC and held at that temperature for 12 hours. Subsequently, the furnace was cooled to room temperature at the rate of 0.4 ºC min-1. Natural tetrahedrite mineral: A natural specimen of tetrahedrite (photograph, Figure S1) was obtained from a mineral dealer [S1]. This specimen, which is identified as tetrahedrite from its geological characteristics, originated from Casapalca region of Peru. It also contained small regions of quartz (small white crystals, Figure S1), and pyrite (not shown in Figure S1).

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The role of Fe2+ and Fe3+ in synthetic Fe-substituted tetrahedrite

Cited by 66 publications

References 11 publications

Crystal Chemistry of Tetrahedrite Solid-Solution: Epr and Magnetic Investigations

Crystal Chemistry of Tetrahedrite Solid-Solution: Epr and Magnetic Investigations

Sulfide geochemistry and genesis of Chouichia and Ain el Bey copper deposits in northwestern Tunisia

High Performance Thermoelectricity in Earth‐Abundant Compounds Based on Natural Mineral Tetrahedrites

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