DOCSLIB.ORG

Greigite (Fe3s4) Is Thermodynamically Stable: Implications for Its Terrestrial and Planetary Occurrence

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Greigite (Fe3s4) Is Thermodynamically Stable: Implications for Its Terrestrial and Planetary Occurrence Greigite (Fe3S4) is thermodynamically stable: Implications for its terrestrial and planetary occurrence Tamilarasan Subramania,1, Kristina Lilovaa,1, Mykola Abramchuka, Kurt D. Leinenwebera, and Alexandra Navrotskya,2 aSchool of Molecular Sciences and Center for Materials of the Universe, Arizona State University, Tempe, AZ 85281 Contributed by Alexandra Navrotsky, September 29, 2020 (sent for review August 18, 2020; reviewed by Robert M. Hazen and Juraj Majzlan) Iron sulfide minerals are widespread on Earth and likely in planetary (16–19), we determined the energetic stability of bulk, nano- bodies in and beyond our solar system. Using measured enthalpies of sized, and high-pressure Fe3S4 phases. We conclude that grei- formation for three magnetic iron sulfide phases: bulk and nanophase gite is a thermodynamically stable phase in the Fe–Ssystem Fe3S4 spinel (greigite), and its high-pressure monoclinic phase, we show near ambient temperature, that it has a low surface energy that greigite is a stable phase in the Fe–S phase diagram at ambient comparable to that of magnetite and other oxide spinels, and temperature. The thermodynamic stability and low surface energy of that the monoclinic phase has a field of thermodynamic sta- greigite supports the common occurrence of fine-grained Fe3S4 in many bility above about 3 GPa. Implications for the occurrence of anoxic terrestrial settings. The high-pressure monoclinic phase, thermo- Fe3S4 in terrestrial and planetary settings are discussed. dynamically metastable below about 3 GPa, shows a calculated nega- tive P-T slope for its formation from the spinel. The stability of these three phases suggests their potential existence on Mercury and their Results and Discussion magnetism may contribute to its present magnetic field. All thermodynamic data in this paper are calculated on the basis of 1 mole of iron to facilitate comparison between different greigite | thermodynamic stability | terrestrial planets | magnetism | iron sulfides. Using the obtained calorimetric data (Table 1), we high pressure calculated the enthalpy of decomposition of greigite to the neighboring phases (pyrite and pyrrhotite) without the involve- ron sulfides are widespread in the Earth and may be important ment of either sulfur or iron as separate phases. The free energy EARTH, ATMOSPHERIC, AND PLANETARY SCIENCES Ion other planets. The spinel mineral greigite Fe3S4, the sulfide of this potential disproportion reaction holds the key to whether analogs of magnetite Fe3O4, has long been considered a meta- greigite is stable or metastable on the iron–sulfur phase diagram. stable phase and a rare mineral (1). Nevertheless, fine-grained Fe3S4 has been reported in a variety of geologic and environ- FeS1.33 → 0.726FeS1.092 + 0.274FeS2 , mental settings. Greigite, mackinawite FeS , and pyrite FeS 0.9 2 ΔH = 18.9 ± 8.6 kJ=mol. can be found in sediments formed as a product of sulfate re- r duction (2). Fine‐grained magnetic iron sulfides such as greigite The reaction is energetically substantially unfavorable and would and pyrrhotite have been reported in marine sediments associ- > ated with anaerobic oxidation of methane and formation of require a positive entropy change of 63.4 J/mol.K at 300 K to methane hydrates (3). Small greigite particles occur in magne- Significance totactic bacteria, which produce both Fe3S4 and Fe3O4 in mag- netosome organelles (4). Greigite is a possible catalyst for CO2 reduction of small organic molecules and for H2 and CO2 fixa- The new experimental thermodynamic studies of bulk, nano- tion, relevant to the origin of life (5, 6). Fe3S4 can possibly host phase, and monoclinic high-pressure forms of greigite (Fe3S4) remanent magnetism, thus potentially contributing to the weak confirm its stability in the Fe–S system and explain its common magnetic field of the planet Mercury (7). Greigite has been occurrence in sediments, magnetotactic bacteria, and other am- reported to form as one of the products in the corrosion of crude bient temperature environments under anoxic conditions. The oil tanks when the rust reacts with H2S gas above the crude oil data disprove the commonly held hypothesis that greigite is a surface (8). Given this widespread occurrence, one must ques- metastable phase. The low surface energy of greigite provides tion the assumptions of rarity and metastability. insight not only into the stability of greigite nanoparticles but The change of mineral properties with particle size has been also into their role in prebiotic, biological, and planetary pro- recognized as a critical aspect of geochemical and biochemical re- cesses. Our experimental data for the stability of the three forms actions in natural systems (9). An important question is whether of Fe3S4 confirm that it could be stable on Mercury, thus con- greigite, a sulfide spinel, has a relatively low surface energy analogous tributing to Mercury’s weak magnetic field. to that of magnetite and other oxide spinels (10, 11). If the surface energy of greigite is lower than that of other sulfides in the Fe–S Author contributions: K.L. and A.N. designed research; T.S., K.L., M.A., K.D.L., and A.N. system, its stability at the nanoscale may be enhanced. Particle-size performed research; T.S., K.L., M.A., K.D.L., and A.N. analyzed data; T.S., K.L., M.A., K.D.L., – – and A.N. wrote the paper; T.S, M.A., and K.D.L. carried out the synthesis, characterization, decrease also results in shift to lower oxygen fugacity of the Fe Si O and surface area measurements of various Fe3S4 phases, did calorimetric measurements, oxygen buffers (11). The sulfur and oxygen fugacities are directly and carried out the synthesis, characterization, and surface area measurements of various linked and control the partitioning of metals between sulfide and Fe3S4 phases. Reviewers: R.M.H., Carnegie Institution for Science; and J.M., Mineralogy Department. oxide phases. Hence, the fS2 and fS2–fO2 buffers could be affected by particle-size effects in the iron sulfides, oxides, and silicates (12). University of Jena. Greigite transforms from a cubic spinel structure to a monoclinic The authors declare no competing interest. Published under the PNAS license. Cr3S4-type structure at 3–4 GPa (13, 14). A natural nanosized 1 monoclinic Fe3S4 phase, probably the same as the reported high- T.S. and K.L. contributed equally to this work. pressure phase, has been found in the Sudbury ore deposit (15). 2To whom correspondence may be addressed. Email: [email protected]. Up to now the thermodynamic properties of greigite have not This article contains supporting information online at https://www.pnas.org/lookup/suppl/ been determined experimentally. Using high-temperature oxide doi:10.1073/pnas.2017312117/-/DCSupplemental. melt solution calorimetric techniques developed for sulfides www.pnas.org/cgi/doi/10.1073/pnas.2017312117 PNAS Latest Articles | 1of4 Downloaded by guest on September 26, 2021 Table 1. Enthalpies of drop solution and of formation from elements of iron sulfide phases per mole of iron Compound ΔHds (kJ/mol) ΔHf,el (kJ/mol) Reference FeS2 (pyrite) −1,471.1 ± 4.2 −175.5 ± 6.0 Xu and Navrotsky, 2010 (16) FeS (troilite) −913.5 ± 3.3 −101.4 ± 4.0 Xu and Navrotsky, 2010 (16) FeS1.092 (pyrrhotite) −966.3 ± 3.3 −106.2 ± 3.5 Xu and Navrotsky, 2010 (16) FeS1.33 (1/3 Fe3S4)* † ‡ Bulk (greigite) −1,071.6 ± 6.2 (6) −144.1 ± 7.3 This work Nanophase (greigite) −1,074.5 ± 4.3 (7) −141.2 ± 5.9 This work High pressure (monoclinic) −1,085.7 ± 5.6 (8) −130.0 ± 6.9 This work *The data reported refer to the molecular formula FeS1.33. † Number of drops given in parentheses; error is 2 SDs of the mean. ‡ The thermochemical cycle used to calculate the enthalpies of formation is given in SI Appendix, Table S2. change the sign of ΔG. Although the standard entropy of greigite The surface energetics of greigite might be important for the is not known, such a large ΔS is very unlikely for a reaction catalytic formation of prebiotic organic molecules on its surface involving only solid phases. We conclude that greigite is a stable and thus for the origin of life according to the iron–sulfur world – phase in the iron sulfur system, at least near ambient tempera- hypothesis (6). The cubic Fe4S4 units resemble 4Fe-4S clusters, ture, and it warrants a place on the equilibrium iron–sulfur phase which are found in the proteins of all living organisms and act as diagram. Greigite is known as an intermediate in pyrite forma- catalysts for synthesis of biomolecules (28). tion, (pyritization) under anoxic sulfate-reducing sedimentary The low oxygen fugacity and the high sulfur concentration conditions (1, 20). Under a diluted carbon supply, the iron spe- recorded during the MESSENGER mission support possible cies will react with sulfide produced by anaerobic decomposition widespread presence of iron sulfide phases on Mercury (29, 30) of organic matter until the reactive iron exhausts the available due to the lack of atmosphere, slow rotation, and high eccen- sulfide and stops the reaction, thus resulting in preservation of tricity, the surface temperature of Mercury varies considerably. greigite (21). The formation of pyrite from greigite will occur, not While the highest temperature on the surface at the equator could because greigite is intrinsically metastable at its own composition, reach 700 K, the temperature at depths below 1 m is modeled to but because excess sulfur is present. Our thermodynamic data sup- be 450 K or less (31), while the temperature in polar craters could port the idea (21) that greigite is a stable compound once formed drop to 100 K. Thus, the surface and near-surface regions of unless there is a change in sulfidizing environment, which explains Mercury are likely to be within the stability field of greigite.
Load more

Recommended publications
  • Arsenian Sphalerite from Mina Ai,Caran, Pampa Larga
    MINERALOGICAL NOTES AMERICAN MINERALOGIST, \IOL. 55, SEPTEMBER.OCTOBER, 1970 ARSENIANSPHALERITE FROM MINA AI,CARAN, PAMPALARGA, COPIAPO, CHILE Arew H. Cr-anr, Department oJ GeologicalSciences, Queen's Uniaersity, Kingston, Ontario, Canado. ABSTRACT Bright pink sphalerite from the arsenic-rich Alacr6n deposit, with a:5.4110 +0.0003 A, is shown by electron-probe microanalysis to contain only traces of iron but 17 +0.3 weight percent As INrnooucrroN The literature containsnumerous reports of appreciablesolid solution of arsenicin sphalerite(e.g. Schroll, 1953; Fleischer,1955), but the an- alytical evidenceremains largeiy unconvincing.Moss (1955;and in Hey, 1955,Frondel, 1967)proposed that the mineral voltzite has the general composition (Zn,As)S or Zn(As,S), but Frondel (1967) subsequently found no evidenceto support this suggestion.Most recent electron- probe microanalysesof sphaleritedo not record even traces of arsentc. Ilowever, Herzenberg(1932,1933) found 0.64 weight percentarsenic by chemical analysisof a raspberry-redsphalerite-like mineral from Llall- agua, Bolivia, which he named gumuc'ionite.Later workers (e.g.Hey, 1955)have assumedthat this material representsa mixture of sphalerite and realgarbut no further work appearsto have been carried out on the original or similar specimens.The presentnote describesthe occurrence of an apparently similar, and demonstrably arsenic-bearingsphalerite. Spner-Bnrrr rN rHE Ar,acnAN DBposrr Sphalerite is a minor constituent of the mineralogically complex, polymetallic Alacr6n vein deposit (Parker, Salas and P6rez, 1963),in the Pampa Larga mining district of northern Chile (Lat. 27"36'5.;Long. 70'11'W.). It occurs, however, in at least three parageneticcontexts: (1) in associationwith early arsenopyrite, pyrite, stibnite, smithite, aAsS (Clark, 1970a)and arsenolamprite(Clark, 1970b), among other minerals; (2) with late-stagegreigite, pyrite, native arsenic,realgar, and orpiment;and (3) rarely, as free-standingcrystals in vugs, in association with realgar and orpiment.
    [Show full text]
  • Using the High-Temperature Phase Transition of Iron Sulfide Minerals As
    www.nature.com/scientificreports OPEN Using the high-temperature phase transition of iron sulfde minerals as an indicator of fault Received: 9 November 2018 Accepted: 15 May 2019 slip temperature Published: xx xx xxxx Yan-Hong Chen1, Yen-Hua Chen1, Wen-Dung Hsu2, Yin-Chia Chang2, Hwo-Shuenn Sheu3, Jey-Jau Lee3 & Shih-Kang Lin2 The transformation of pyrite into pyrrhotite above 500 °C was observed in the Chelungpu fault zone, which formed as a result of the 1999 Chi-Chi earthquake in Taiwan. Similarly, pyrite transformation to pyrrhotite at approximately 640 °C was observed during the Tohoku earthquake in Japan. In this study, we investigated the high-temperature phase-transition of iron sulfde minerals (greigite) under anaerobic conditions. We simulated mineral phase transformations during fault movement with the aim of determining the temperature of fault slip. The techniques used in this study included thermogravimetry and diferential thermal analysis (TG/DTA) and in situ X-ray difraction (XRD). We found diversifcation between 520 °C and 630 °C in the TG/DTA curves that signifes the transformation of pyrite into pyrrhotite. Furthermore, the in situ XRD results confrmed the sequence in which greigite underwent phase transitions to gradually transform into pyrite and pyrrhotite at approximately 320 °C. Greigite completely changed into pyrite and pyrrhotite at 450 °C. Finally, pyrite was completely transformed into pyrrhotite at 580 °C. Our results reveal the temperature and sequence in which the phase transitions of greigite occur, and indicate that this may be used to constrain the temperature of fault-slip. This conclusion is supported by feld observations made following the Tohoku and Chi-Chi earthquakes.
    [Show full text]
  • FREE MACKINAWITE FREE SULFIDATED IRON When and Where You Want It
    FREE MACKINAWITE FREE SULFIDATED IRON when and where you want it REACTIVE IRON SULFIDES As reviewed by Fan et al., (2017), multiple studies have shown that various reactive iron sulfide species can aid in the biogeochemical transformation of organic constituents of interest (COIs) such as halogenated organic solvents, and that they can be useful in precipitating inorganic COIs such as arsenic, chromium and mercury. This is most apparent with nanoscale or fine (e.g., < 10 micron) zero valent iron (ZVI) particles because they have more surface area which can be quickly passivated, hence within a short period of time, they typically exhibit lower efficiency for dechlorination. In an effort to mitigate this phenomenon various formulations of sulfidated iron (S-ZVI) and other reactive iron sulfide species such as mackinawite per se have become available commercially as remedial amendments designed to be injected or otherwise applied directly to an impacted environment. The reactive properties of S-ZVI adhere to classic corrosion chemistry principles governing the conditions under which sulfur attacks iron. Recognizing the potential distinctions between chemical sulfidation and natural sulfidation, an alternative means of harnessing the activity of reactive iron sulfides - instead of buying mackinawite alone (for example) - is to generate multiple iron sulfide species, in place, and for free as part of an engineered remedial amendment that integrates multiple synergistic biogeochemical reactions (see Mangayayam et al, 2019 for emerging insights into the actual value of buying and applying sulfidated iron products directly). In so doing the remedial actions occur where they are needed and not simply where the insoluble precipitates are directly emplaced.
    [Show full text]
  • ANHYDROUS SYNTHESIS of GREIGITE. Fe3s4
    MINERALOGICAL JOURNAL, VOL. 6, No. 6, pp. 458-463, APRIL 1972 ANHYDROUS SYNTHESIS OF GREIGITE. Fe3S4 HIROMOTO NAKAZAWA and KouSUKE SAKAGUCHI National Institute for Researches in Inorganic Materials, Kurakake, Sakura-mura, Niihari-gun, Ibaragi, Japan ABSTRACT The vacuum evaporation method has been applied for preparation of low-temperature phases of iron sulfides. Thin films were synthesized from natural pyrrhotite crystals on cleaved halite crystals heated at different temperatures. The films have been identified by the electron diffraction method to be greigite, Fe3S4. Presence of a small amount of marcasite has been also confirmed in the films prepared on halite crystals at room tem perature. Introduction The phase relations of the iron-sulfur system were recently studied below 320•Ž in detail (Morimoto et al., 1970; Nakazawa & Morimoto, 1971). However, the relations have not been completely settled at relatively low temperatures, because the reaction rate was very slow in the usual dry synthesis of the iron sulfides stable in nature. In order to study the phase relations in more details, it is indispensable to produce low temperature phases under known conditions and to examine their properties. For the preparation of the low-temperature phases in dry condition, the vacuum evapora tion method was considered to be useful, because the evaporated atoms or molecules were considered to deposit on the substrate of low temperatures and crystallize into low-temperature phases. In this investigation, greigite and marcasite have been success- fully synthesized by vacuum evaporation technique as examples of H. NAKAZAWA and K . SAKAGUCHI 459 dry synthesis of low-temperature phases of the iron -sulfur system .
    [Show full text]
  • Characterisation of Iron (II) Sulfides in Wet Archaeological Woods: The
    Characterisation of iron (II) sulfides in wet archaeological woods: the wreck of Mandirac (IV th century, antique ports of Narbonne, France) Céline Remazeilles, Francois Leveque, Maylis Minjacq, Philippe Refait, Corinne Sanchez, Marie-Pierre Jézégou To cite this version: Céline Remazeilles, Francois Leveque, Maylis Minjacq, Philippe Refait, Corinne Sanchez, et al.. Char- acterisation of iron (II) sulfides in wet archaeological woods: the wreck of Mandirac (IV th century, antique ports of Narbonne, France). WOAM 2016, May 2016, Florence, Italy. hal-02345869 HAL Id: hal-02345869 https://hal-univ-rochelle.archives-ouvertes.fr/hal-02345869 Submitted on 4 Nov 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Characterisation of iron (II) sulfides in wet archaeological woods: the wreck of Mandirac (IVth century, antique ports of Narbonne, France) Céline Rémazeillesa*, François Lévêqueb, Maylis Minjacqab, Philippe Refaita, Corinne Sanchezc, Marie-Pierre Jézégoud aLaSIE, Laboratory of Engineering Sciences for the Environment UMR 7356 CNRS/University of La Rochelle [email protected] bLIENSs, Littoral, Environment and Societies UMR 7266 CNRS/University of La Rochelle cASM, Archaeology of Mediterranean Societies UMR-5140 CNRS/University of Montpellier Ministry of Culture and Communication/INRAP, French National Institute for Preventive Archaeological Research dDRASSM, Department for Underwater and Undersea Archaeological Research Abstract The wreck of Mandirac (Narbonne, France, IV century) was excavated in 2013 and 2014 from waterlogged soil.
    [Show full text]
  • Iron Sulfides from Magnetotactic Bacteria: Structure, Composition
    American Mineralogist, Volume 83, pages 1469-1481, 1998 Iron sulfidesfrom magnetotacticbacteria: Structure, composition, and phasetransitions Mrnfu,v PosrlIr''x Pprnn R. Busrcrrl DENNTsA. BlzyLrNSKrr2aNo RrcnlRD B. FnaNrrl3 lDepaftmentsof Geology and Chemistry/Biochemistry,Arizona State University, Tempe,Arizona 85287, U.S.A. '?Departmentof Microbiology, Immunology and PreventiveMedicine, Iowa State University, Ames, Iowa 50011, U.S.A. rDepartmentof Physics,Californa Polytechnic State University, San Luis Obispo, California 93407, U.S A. AesrRAcr Using transmissionelectron microscopy, we studied the structuresand compositionsof Fe sulfides within cells of magnetotacticbacteria that were collected from natural habitats. Ferrimagnetic greigite (Fe.S.) occurred in all types of sulfide-producing magnetotactic bacteriaexamined. Mackinawite (tetragonalFeS) and, tentatively, sphalerite-typecubic FeS were also identified. In contrastto earlier reports,we did not find pyrite (FeSr)or pyrrhotite (Fe, ,S). Mackinawite converted to greigite over time within the bacteria that were de- posited on electron microscope grids and stored in air. Orientation relationshipsbetween the two minerals indicate that the cubic-close-packedS substructureremains unchanged during the transformation; only the Fe atoms rearrange. Neither mackinawite nor cubic FeS are magnetic, and yet they are aligned in chains such that when convertedto magnetic greigite, the probable easy axis of magnetization, [100], is parallel to the chain direction. The resulting chains of greigite
    [Show full text]
  • What Do We Really Know About the Role of Microorganisms in Iron Sulfide Mineral Formation?
    What Do We Really Know about the Role of Microorganisms in Iron Sulfide Mineral Formation? The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Picard, Aude, Amy Gartman, and Peter R. Girguis. 2016. What Do We Really Know About the Role of Microorganisms in Iron Sulfide Mineral Formation? Front. Earth Sci. 4. doi:10.3389/ feart.2016.00068. Published Version doi:10.3389/feart.2016.00068 Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:30653602 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA MINI REVIEW published: 15 June 2016 doi: 10.3389/feart.2016.00068 What Do We Really Know about the Role of Microorganisms in Iron Sulfide Mineral Formation? Aude Picard 1*, Amy Gartman 2* and Peter R. Girguis 1 1 Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA, 2 U. S. Geological Survey, Santa Cruz, CA, USA Iron sulfide mineralization in low-temperature systems is a result of biotic and abiotic processes, though the delineation between these two modes of formation is not always straightforward. Here we review the role of microorganisms in the precipitation of extracellular iron sulfide minerals. We summarize the evidence that links sulfur-metabolizing microorganisms and sulfide minerals in nature and we present a critical overview of laboratory-based studies of the nucleation and growth of iron sulfide minerals in microbial cultures.
    [Show full text]
  • Magnetostratigraphic Importance of Secondary Chemical Remanent Magnetizations
    Results of IODP Expedition 313: The History and Impact of Sea-Level Change Offshore New Jersey Themed Issue Magnetostratigraphic importance of secondary chemical remanent magnetizations carried by greigite (Fe3S4) in Miocene sediments, New Jersey shelf (IODP Expedition 313) Andreas Nilsson1, Youn Soo Lee2, Ian Snowball3,4, and Mimi Hill1 1The Geomagnetism Laboratory, School of Environmental Sciences, University of Liverpool, Oxford Street, Liverpool L69 7ZE, UK 2Department of Geology and Geoinformation, Korea Institute of Geoscience and Mineral Resources (KIGAM), 30 Gajeong-dong Yuseong-gu, Daejeon, 305-350, South Korea 3Geophysics, Department of Earth Sciences, Uppsala University, Villavägen 16, 752 36 Uppsala, Sweden 4Department of Geology, Lund University, Sölvegatan 12, 223 62 Lund, Sweden ABSTRACT et al., 1993; Mann et al., 1990; Vasiliev et al., shelf (Oda and Torii, 2004), some samples con- 2008). Kao et al. (2004) suggested that greigite tain evidence for gyroremanent magnetization Paleomagnetic and mineral magnetic preservation is favored by conditions with high (GRM) acquisition, which can be indicative of analyses were carried out on Miocene clays concentrations of reactive iron in fi ne-grained the presence of greigite (Snowball, 1997). from upper unit II at Sites M0027 and M0028 sediments with limited organic carbon supply. In this study, we attempted to identify the recovered during Integrated Ocean Drilling In such cases, the reactive iron exhausts supply main magnetic minerals in the Miocene clay- Program Expedition 313 on the New Jersey of dissolved sulfi de so effectively that the pyriti- rich horizons from Expedition 313. Through shallow shelf. A zone of mixed polarity in the zation process is arrested.
    [Show full text]
  • The Koman Dawsonite and Realgar–Orpiment Deposit, Northern Albania
    413 The Canadian Mineralogist Vol. 41, pp. 413-427 (2003) THE KOMAN DAWSONITE AND REALGAR–ORPIMENT DEPOSIT, NORTHERN ALBANIA: INFERENCES ON PROCESSES OF FORMATION VINCENZO FERRINI§ Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza”, P.le A. Moro, 5, I–00185 Roma, Italy LUCIO MARTARELLI Centro di Studio per gli Equilibri Sperimentali in Minerali e Rocce del C.N.R., P.le A. Moro, 5, I–00185 Roma, Italy CATERINA DE VITO Dipartimento di Scienze della Terra, Università degli Studi di Roma “La Sapienza”, P.le A. Moro, 5, I–00185 Roma, Italy ALEKSANDER ÇINA AND TONIN DEDA Geological Survey of Albania, Rruga Vasil Shanto, Tirana, Albania ABSTRACT The deposit of dawsonite and realgar–orpiment in the Koman area, northern Albania, is aligned along the NE–SW-trending tectonic line joining the Krasta–Cukal and Mirdita structural-tectonic zones. The deposit contains the following main paragenetic assemblages: i) marcasite – greigite (Fe-sulfide stage), ii) stibnite – realgar – orpiment (As–Sb-sulfide stage), iii) dolomite – calcite – dawsonite – aragonite – barite – gypsum (carbonate–sulfate stage), iv) native As – gibbsite (supergene stage). There was lithostratigraphic control of mineralization; carbonate-rich wallrocks reacted with the mineralizing fluids emanating from a bur- ied magmatic body and migrating along Albanian transversal faults, rather than argillaceous lithotypes. Values of ␦18O and ␦13C indicate that dawsonite and hydrothermal dolomite are derived at the expense of carbonate rocks, which occur extensively in the stratigraphic sequence of the host rocks. The water:rock ratio during the carbonate–sulfate stage of deposition was probably small. Moreover, oxygen and carbon isotopic exchange during metasomatic transformation of the rocks, recrystallization and late involvement of groundwater, probably all occurred.
    [Show full text]
  • Identification of Ferromagnetic Minerals
    IDENTIFICATION OF FERROMAGNETIC MINERALS MAGNETIC MINERAL ANALYSIS OF PANNONIAN, SARMATIAN AND BADENI AN (10.5-13.7 MA) SEDIMENTS FROM THE SPANNBERG 21 WEL L (EBENTHAL, AUSTRIA) BSC - THESIS G.J.H.M. KOOLEN D E L F T , FEBRUARI ‟10 ABSTRACT The magnetic mineral content of marine and fluviatile sediments in the Vienna Basin, Austria has been measured and described. The magnetic signal measured in a well records the earth‟s magnetic field during deposition of the sediments. Two main ferromagnetic minerals, magnetite and greigite, are found as the dominant natural remanent magnetism carriers. In this study magnetite bearing samples were distinguished from greigite bearing samples. In more than 75% of the samples it was legitimate to decide upon IRM and Curie measurements whether the sample consisted mainly of magnetite or greigite. For the uncertain part of the samples additional experiments were carried out to further determine the mineral content. One of the data processing steps, the construction of IRM components analysis graphs, was rather subjective. Finally it was found that at certain depths the natural remanent magnetism is small because of a small magnetic mineral content. Later formed authigenic greigite is able to lower the overall remanent magnetization due to having an opposite polarity than the polarity being present in the earlier deposited magnetic minerals. 2 ACKNOWLEDGEMENTS I would like to thank my academic supervisor of this work ir. W.E. Paulissen, Department of Geotechnology, Delft University of Technology, Delft for her kind supervision, for providing sufficient information required for this thesis and especially for her faith in me and my BSc- project.
    [Show full text]
  • STRUCTURE, MORPHOLOGY and GROWTH of BIOGENIC GREIGITE (Fe3s4) B.R
    93 STRUCTURE, MORPHOLOGY AND GROWTH OF BIOGENIC GREIGITE (Fe3S4) B.R. Heywood", S. Manna and R.B. Frankelb aSchool of Chemistry, University of Bath, Bath BA2 7AY, UK. bDepartment of Physics, California Polytechnic State University, San Luis Obispo, CA 93407, USA. ABSTRACT Several species of aquatic bacteria are known to exploit the earth's geomagnetic field as a means of directing their motion towards suitable habitats. A feature common to these bacteria is the presence of discrete intracellular magnetic inclusions, magnelosomes, aligned in chains along the long axis of the organism. The size and orientation of the individual magnetic particles imparts a permanent magnetic dipole moment to the cell which is, in turn, responsible for the magnetotactic response. In all species examined to date the magnetic particles have been found to be well-ordered, single domain, membrane-bounded crystals with reproducible, species-specific morphologies. Until recently, however, only crystals of the mixed valence iron oxide, magnetite (Fe304), were identified in these magnetotactic bacteria. We have now identified three species of bacteria from sulphidic environments which contain crystals of the mixed valence ferrimagnetic iron sulphide, greigite (Fe3S4)' High resolution electron microscopical studies of the biogenic greigite crystals showed that they also exhibit the narrow size range (50-90nm) and unique crystallographic habits (e.g. cubo-octahedral, rectangular prismatic) which characterized and distinguished the inclusions in other magnetotactic species. Thus, it would appear that the bio-precipitation of iron sulphides in magnetotactic bacteria is a highly regulated process which is directed and controlled at the molecular level. These findings are not only important to our understanding of biomineralization in unicellular organisms but may also be significant to studies of paleomagnetism.
    [Show full text]
  • Mineralogy of Sulfides
    This is a repository copy of Mineralogy of sulfides. White Rose Research Online URL for this paper: http://eprints.whiterose.ac.uk/113362/ Version: Published Version Article: Vaughan, D.J. and Corkhill, C.L. orcid.org/0000-0002-7488-3219 (2017) Mineralogy of sulfides. Elements , 13 (2). pp. 81-87. ISSN 1811-5209 https://doi.org/10.2113/gselements.13.2.81 Reuse This article is distributed under the terms of the Creative Commons Attribution (CC BY) licence. This licence allows you to distribute, remix, tweak, and build upon the work, even commercially, as long as you credit the authors for the original work. More information and the full terms of the licence here: https://creativecommons.org/licenses/ Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ Mineralogy of Sulfides David J. Vaughan1 and Claire L. Corkhill2 1811-5209/17/0013-0081$2.50 DOI: 10.2113/gselements.13.2.81 etal sulfides are the most important group of ore minerals. Here, we The literature on sulfide minerals review what is known about their compositions, crystal structures, is extensive, with a number of overview textbooks and Mphase relations and parageneses. Much less is known about their monographs. Comprehensive surface chemistry, their biogeochemistry, or the formation and behaviour of reviews can be found in Ribbe ‘nanoparticle’ sulfides, whether formed abiotically or biogenically.
    [Show full text]