Hostname: page-component-745bb68f8f-d8cs5 Total loading time: 0 Render date: 2025-02-06T05:52:12.914Z Has data issue: false hasContentIssue false
  • English
  • Français

Composition of tetrahedrite-tennantite and ‘schwazite’ in the Schwaz silver mines, North Tyrol, Austria

Published online by Cambridge University Press:  05 July 2018

T. Arlt  and
L. W. Diamond
T. Arlt
Affiliation:
Mineralogisch-petrographisches Institut, Universität Bern, Baltzerstrasse 1, CH-3012 Bern, Switzerland
L. W. Diamond
Affiliation:
Mineralogisch-petrographisches Institut, Universität Bern, Baltzerstrasse 1, CH-3012 Bern, Switzerland
Get access Rights & Permissions [Opens in a new window]

Abstract

The hydrothermal fahlore deposits of the Schwaz-Brixlegg district have been mined for silver and copper over many centuries and are famous as the type locality of the mercurian fahlore variety ‘schwazite’. The ore is dominantly monomineralic fahlore and occurs as stratabound, discordant vein, and breccia bodies over a 20 km belt hosted mostly by the Devonian Schwaz Dolomite. The structural style of the mineralization is similar to that of Mississippi Valley type deposits.

This study presents the first electron microprobe analyses of the ores and reveals wide variations in fahlore compositions, from 35 to 100 wt.% tetrahedrite end-member in the solid solution series with tennantite. Sb and Zn contents vary between 12.1–28.0 wt.% and 0.1–7.6 wt.%, respectively. Silver contents average 0.5 wt.% and range up to 2.0 wt.%. In the breccia-hosted ores these variations clearly result from a temporal evolution in the ore-forming hydrothermal system: main-stage tetrahedrite is replaced by assemblages of Sb-, Fe-, and Ag-enriched tetrahedrite + enargite, with minor sphalerite ± stibnite ± cuprian pyrite (≤ 25 wt.% Cu). These reactions are deduced to result from either increases in aqueous sulphur activity or falling temperature. Earlier workers recognized strong geographic zonation of fahlore compositions, but our microprobe analyses refute these contentions.

The 1167 new microprobe analyses of 51 fahlore samples collected underground or obtained from museum collections yield an average Hg content of 1.8 wt.%, and a maximum of 9.4 wt.%. According to modern nomenclature, not even the highest Hg value qualifies as ‘schwazite’. Moreover, it appears that the original and only analysis of ‘schwazite’, reporting 15.6 wt.% Hg (Weidenbusch, 1849), was erroneously performed on a polymineralic aggregate, rather than on a monomineralic fahlore. We conclude that the Schwaz-Brixlegg fahlores are in fact not unusually rich in mercury, and that in all probability there is not, and never has been, any ‘schwazite’ at Schwaz.

Keywords

BrixleggenargitefahloremercurySchwazschwazitefukuchilitesilvertetrahedrite-tennantite
Type
Research Article
Information
Mineralogical Magazine , Volume 62 , Issue 6 , December 1998 , pp. 801 - 820
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1998

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

*

Present address: Bayerisches Geoinstitut, Universität Bayreuth, D-95440 Bayreuth, Germany

References

Arlt, T. and Diamond, L.W. (1996) Composition and formation conditions of tetrahedrite-tennantite in the Devonian Schwaz Dolomite, N-Tyrol, Austria. Mitt. Österr. Mineral. Ges., 141, 58-9.Google Scholar
Atanasov, V.A. (1975) Argentian mercurian tetrahedrite, a new variety, from the Chiprovtsi ore deposit, Western Stara-Planina mountains, Bulgaria. Mineral. Mag., 40, 233-7.CrossRefGoogle Scholar
Barton, P.B. and Skinner, B.J. (1979) Sulfide Mineral Stabilities. In Geochemistry of Hydrothermal Ore Deposits, (Barnes, H.L., ed.). John Wiley & Sons, New York. 278–403.Google Scholar
Breskovska, V. and Tarkian, M. (1994) Compositional Variation in Bi-Bearing Fahlores. Neues Jahrb. Mineral. Mh., 230-40.Google Scholar
Charlat, M. and Lèvy, C. (1974) Substitutions multiples dans la série tennantite-tetraédrite. Bull. Soc. franç. Minéral. Cristallogr., 97, 241-50.CrossRefGoogle Scholar
Charnock, J.M., Garner, C.D., Pattrick, R.A.D. and Vaughan, D.J. (1989) Coordination Sites of Metals in Tetrahedrite Minerals determined by EXAFS. J. Solid State Chem., 82, 279-89.CrossRefGoogle Scholar
Dana, E.S. (1896) The System of Mineralogy, 6th edition, 1134 pp.Google Scholar
Ebel, D.S. and Sack, R.O. (1991) Arsenic-silver incompatibility in fahlore. Mineral. Mag., 55, 521-8.CrossRefGoogle Scholar
Faick, J.H. (1958) Geology of the Ord Mine, Mazatzal Mountains Quicksilver District, Arizona. Geol. Surv. Bull., 1042-R.Google Scholar
Frimmel, H.E. (1991) Isotopic constraints on fluid/rock ratios in carbonate rocks: Barite-sulfide mineralization in the Schwaz Dolomite, Tyrol (Eastern Alps, Austria). Chem. Geol., 90, 195–209.CrossRefGoogle Scholar
Frimmel, H.E. and Papesch, W. (1990) Sr, O, and C Isotope Study of the Brixlegg Barite Deposit, Tyrol (Austria). Econ. Geol., 85, 1162-71.CrossRefGoogle Scholar
Götzinger, M.A., Paar, W.H. and Schroll, E. (1997) 2.3. Fahlerz. In: Handbuch der Lagerstätten der Erze, Industrieminerale und Energierohstoffe Ö sterreichs (Weber, L., ed.) Archiv für Lagerstättenforschung, 19, 407-14.Google Scholar
Grundmann, G. and Martinek, K.-P. (1994) Erzminerale und Gangarten des Bergbaugebietes Schwaz und Brixlegg. Lapis, 19, 28–37.Google Scholar
Gstrein, P. (1978) Neuerkenntnisse über die Genese der Fahlerzlagerstätte Schwaz (Tirol). Unpub. PhD Dissertation, Univ. Innsbruck, 380 pp.CrossRefGoogle Scholar
Gstrein, P. (1979) Neuerkenntnisse über die Genese der Fahlerzlagerstätte Schwaz (Tirol ). Mineral. Deposita, 14, 185-94.CrossRefGoogle Scholar
Gstrein, P. (1983) Über mögliche Umlagerungen von Fahlerzen im devonischen Schwazer Dolomit wie auch in der angrenzenden Schwazer Trias. Schriftenreihe d. Erdwiss. Kommission (Austria), 6, 65–73.Google Scholar
Hackbarth, C. J. and Petersen, U. (1984) A fractional crystallization model for the deposition of argentian tetrahedrite. Econ. Geol., 79, 448-60.CrossRefGoogle Scholar
Haditsch, J. G. and Mostler, H. (1969) Die Fahlerzlagerstätte auf der Gratlspitz (Thierberg bei Brixlegg). Archiv f. Lagerstättenforschung i. d. Ostalpen, 9, 169-94.Google Scholar
Harris, D.C. (1990) Electron-microprobe analysis. In Advanced Microscopic Studies of Ore Minerals (Jambor, J.L. and Vaughan, D.J., Eds). Mineral. Assoc. Canada Short Course Handb., 17, 319-39.Google Scholar
Heidtke, U. (1984) Die Mineralien des Landsberges bei Obermoschel (Pfalz) unter besonderer Berücksichtigung der Silberamalgame. Aufschluss, 35, 191–205.Google Scholar
Isser, M.v. (1905) Schwazer Bergwerks-Geschichte. Eine Monographie über die Schwazer Erzbergbaue. Manuscript, Museum Ferdinandeum, Innsbruck, 354 pp.Google Scholar
Johnson, N.E., Craig, J.R. and Rimstidt, J.D. (1986) Compositional trends in tetrahedrite. Canad. Mineral., 24, 385-97.Google Scholar
Kajiwara, Y. (1969) Fukuchilite, a new mineral from the Hanawa Mine, Akita Prefecture, Japan. Mineral. J., 5, 399–416.CrossRefGoogle Scholar
Kalbskopf, R. (1971) Die Koordination des Quecksilbers im Schwazit. Tschermaks Mineral. Petrog. Mitt. 16, 173-5.CrossRefGoogle Scholar
Kaplunnik, L.N., Pobedimskaya, E.A. and Belov, N.V. (1980) The crystal struct ure of Schwazi te (Cu4.4Hg1.6)Cu6Sb4S12 . Dokl. Akad. Nauk SSSR, 253, 105-7.Google Scholar
Kenngott, G.A. (1853) Das Mohs'sche Mineralsystem, dem gegenwärtigen Standpuncte der Wissenschaft gemäss bearbeitet, Wien.Google Scholar
Krischker, G.A. (1990) Die Baryt-Fahlerz-Lagerstätte St. Gertraudi/Brixlegg. Unpub. Diploma Thesis, Univ. Innsbruck. 206 pp.Google Scholar
Lengauer, C.L. (1988 a) Geologie und Erzmineralogie der Lagerstätte Leogang, Salzburg. PhD Thesis, Univ. Salzburg, 146 pp.Google Scholar
Lengauer, C.L. (1988 b) Zur Metamorphose der westlichen Grauwackenzone (Salzburg). Abstract. Österreich Geol. Gesell. Ann. Mtg., 15–16.Google Scholar
Lynch, J.V.G. (1989) Large-scale hydrothermal zoning reflected in the tetrahedrite-freibergite solid solution, Keno Hill Ag-Pb-Zn district, Yukon. Canad. Mineral., 27, 383–400.Google Scholar
Miller, J.W. and Craig, J.R. (1983) Tetrahedritetennantite series compositional variations in the Cofer Deposit, Mineral District, Virginia. Amer. Mineral., 68, 227-34.Google Scholar
Moh, G.H. (1989) Ore Minerals: An experimental Approach - and new observation. Neues Jahrbuch Mineral., Abh., 160, 1–69.Google Scholar
Mostler, H. (1984) An jungpaläozoischen Karst gebundene Vererzungen mit einem Beitrag zur Genese der Siderite des Steirischen Erzberges. Geol. Paläont. Mitt. Innsbruck, 13, 97–111.Google Scholar
Mozgova, N.N., Tsepin, A.I. and Ozerova, N.A. (1980) Arsenic Schwazite. Dokl. Acad. Sci. USSR; Earth Sci. Sect., 239, 143-6.Google Scholar
Neuninger, H., Pittoni, R. and Preuschen, E. (1960) Das Kupfer der Nordtiroler Urnenfelderkultur. Archaeologica Austriaca, Beih. 5, 1–89.Google Scholar
Oudin, E., Marchig, V., Rösch, H., Lolou, C. and Brichet, E. (1990) Observation de CuS2 à l'état naturel dans une cheminée hydrothermal e du Pacifique Sud. C. R. Acad. Sci. Paris, 310, Serie II, 221-6.Google Scholar
Pattrick, R.A.D. and Hall, A.J. (1983) Silver substitution into synthetic zinc, cadmium and iron tetrahedrites. Mineral. Mag., 47, 441-51.CrossRefGoogle Scholar
Pirkl, H. (1961) Geologie des Triasstreifens und des Schwazer Dolomits südlich des Inn zwischen Schwaz und Wörgl (Tirol). Jahrb. Geol. Bundesanstalt (Austria), 104, 1–150.Google Scholar
Pouchou, J.L. and Pichoir, F. (1984) Un nouveau modèle de calcul pour la microanalyse quantitative par spectrométrie de rayons X. La Recherche Aérospatiale, 3, 167-92.Google Scholar
Rammelsberg, C.F. (1849) Repertorium des Chemischen Theils der Mineralogie. 4th Suppl., 66-7.Google Scholar
Sack, R.O. (1992) Thermochemistry of tetrahedritetennantite fahlores. In The Stability of Minerals (Ross, N.L. and Price, G.D., eds), Chapman and Hall, London, 243-66.Google Scholar
Schmid-Beurmann, P. and Bente, K. (1995) Stability properties of the CuS2-FeS2 solid solution series of pyrite type. Mineral. Petrol., 53, 333-41.CrossRefGoogle Scholar
Schmidegg, O. (1951) Die Erzlagerstätten des Schwazer Bergbaugebietes, besonders des Falkenstein. Schlern-Schriften, 85, 36–58.Google Scholar
Schober, C. (1984) Zur Geologie der Schwazer Trias und des Schwazer Dolomits (Tirol) unter besonderer Berücksichtigung der Vererzung. Unpub. PhD Dissertation, Univ. Innsbruck, 186 pp.Google Scholar
Schroll, E. (1979) Beitrag der Geochemie zur Kenntnis der Lagerstätten der Ostalpen. Geol. Bundesanstalt (Austria) Verh., 1978, 461-70.Google Scholar
Schroll, E. and Azer Ibrahim, N. (1959) Beitrag zur Kenntniss ostalpiner Fahlerze. Tschermaks Mineral. Petrog. Mitt., 7, 70–105.CrossRefGoogle Scholar
Schulz, O. (1972) Unterdevonische Baryt-Fahlerz- Mineralisation und ihre steilachsige Verformung im Grosskogel bei Brixlegg (Tirol). Tschermaks Mineral. Petrog. Mitt., 18, 114-28.CrossRefGoogle Scholar
Schulz, O. (1979) Metallogenese in den österreichischen Ostalpen. Geol. Bundesanstalt (Austria) Verh. 1978, 471-8.Google Scholar
Seal, R.R., Essene, E.J. and Kelly, W.C. (1990) Tetrahedrite and tennantite: evaluation of thermodynamic data and phase equilibria. Canad. Mineral., 28, 725-38.Google Scholar
Shimazaki, H. and Clark, L.A. (1970) Synthetic FeS2–CuS2 solid-solution and fukuchilite- like minerals. Canad. Mineral., 10, 648-64.Google Scholar
Tufar, W. (1979) Mikroskopisch-lagerstättenkundliche Charakteristik ausgewählter Erzparagenesen aus dem Altkristallin, Paläozoikum und Mesozoikum der Ostalpen. Geol. Bundesanstalt (Austria) Verh. 1978, 499–528.Google Scholar
Vasil'yev, V.I. and Lavrent'yev, Y.G. (1973) Mercury-bearing tennantite. Dokl. Acad. Sci. USSR, Earth Sci. Sect., 218, 111-3.Google Scholar
Vohryzka, K. (1968) Die Erzlagerstätten von Nordtirol und ihr Verhältnis zur alpinen Tektonik. Jahrb. Geol. Bundesanstalt (Austria), 111, 3–88.Google Scholar
Weidenbusch, H. (1849) Analyse des quecksilberhaltigen Fahlerzes von Schwatz in Tyrol. In Annalen der Physik und Chemie (Poggendorff, J.C., ed.), 3. Reihe, 16, 86-8.CrossRefGoogle Scholar
Wu, I. and Petersen, U. (1977) Geochemistry of tetrahedrite and mineral zoning at Casapalca, Peru. Econ. Geol., 72, 993–1016.CrossRefGoogle Scholar
Zepharovich, V.v. (1859) Mineralogisches Lexikon für das Kaiserthum Österreich. Band 1, Wien, Verlag Milhelm Braumüller (Reprint Graz, 1985), 388-9.Google Scholar