Tungsten mineralization in hydrothermal quartz veins from the Nyakabingo,Gifurwe and Bugarama deposits in central Rwanda occurs as the iron-rich endmember ofthe wolframite solid solution series (ferberite) and in the particular form of reinite, whichrepresents a pseudomorph of ferberite after scheelite. Primary ferberite, reinite and latesecondary ferberite are characterized by their trace element chemistry and rare earthelement patterns. The replacement of scheelite by ferberite is also documented in the traceelement composition. Primary ferberite shows high Mg, Zn, Sc, V, Nb, In and Snconcentrations, but very low Ca, Pb, Sr and Ba contents. Reinite and late secondaryferberite display an uncommon trace element composition containing high concentrationsof Ca, Pb, Sr, Ba, As and Ga, but very low levels in Sn, Zr, Hf, In, Ti, Sc, Nb, Ta, Mg andZn. Late secondary ferberite replacing primary ferberite is characterized by additionalenrichments in Bi, Pb, As and Sb. The rare earth element patterns of reinite and secondaryferberite are also similar to hydrothermal scheelite. The formation of the tungsten depositsin central Rwanda is interpreted to be epigenetic in origin, and the hydrothermalmineralizing fluids are related to the intrusion of the G4-granites.
References
[1]
Varlamoff, N. Les gisements de tungstène au Congo belge et au Ruanda-Urundi [in French]. Acad. R. Sci. Colon. Cl. Sci. Nat. Méd. Mém. Nouv. Sér. 1958, 8, 1–70.
[2]
Frisch, W. Die Wolfram-Lagerst？tte Gifurwe (Rwanda) und die Genese der zentralafrikanischen Reinit-Lagerst？tten [in German]. Jahrb. Geol. Bundesanst. 1975, 118, 119–191.
[3]
Pohl, W. Zur Geologie der Wolframlagerst？tte Bugarama, Rwanda Afrika [in German]. Jahrb. Geol. Bundesanst. 1976, 119, 129–149.
[4]
Sahama, T.G. The secondary tungsten minerals, a review. Mineral. Rec. 1981, 12, 81–87.
[5]
De Clercq, F. Metallogenesis of Sn and W Vein-Type Deposits in the Karagwe-Ankole Belt. Ph.D. Thesis, Katholieke Universiteit Leuven, Leuven, Belgium, September 2012.
De Magnée, I.; Aderca, B. Contribution à la connaissance du Tungsten-belt ruandais [in French]. Acad. R. Sci. Colon. Cl. Sci. Nat. Méd. Mém. Nouv. Sér. 1960, 11, 1–56.
[9]
Cheilletz, A. Stratiform tungsten deposits: A review. Geol. Mijnb. 1988, 67, 293–311.
[10]
Günther, M.A. Flüssigkeitseinschlüsse und Geologisches Umfeld Zentralafrikanischer Sn-, W- und Au-Lagerst？tten (Rwanda und Burundi) [in German]. Ph.D. Thesis, Technical University Braunschweig, Braunschweig, Germany, January 1990.
[11]
Pohl, W. Metallogeny of the northeastern Kibara belt, Central Africa—Recent perspectives. Ore Geol. Rev. 1994, 9, 105–130, doi:10.1016/0169-1368(94)90024-8.
[12]
De Clercq, F. Petrografische, Mineralogische en Geochemische Studie van de Wolfraammineralisaties van Nyakabingo en Gifurwe (Rwanda) [in Dutch]. Master’s Thesis, Katholieke Universiteit Leuven, Leuven, Belgium, June 2007.
[13]
De Clercq, F.; Muchez, P.; Dewaele, S.; Boyce, A. The tungsten mineralization at Nyakabingo and Gifurwe (Rwanda): Preliminary results. Geol. Belg. 2008, 11, 251–258.
[14]
Fletcher, C.J.N. The geology, mineralization, and alteration of Ilkwang mine, Republic of Korea: A Cu-W-bearing tourmaline breccias pipe. Econ. Geol. 1977, 72, 753–768, doi:10.2113/gsecongeo.72.5.753.
[15]
Van Horn, F.R. Replacement of wolframite by scheelite with observations on the fluorescence of certain tungsten minerals. Am. Mineral. 1930, 15, 461–469.
[16]
Tack, L.; Wingate, M.T.D.; De Waele, B.; Meert, J.; Belousova, E.; Griffin, B.; Tahon, A.; Fernandez-Alonso, M. The 1375 Ma “Kibaran Event” in Central Africa: Prominent emplacement of bimodal magmatism under extensional regime. Precambrian Res. 2010, 180, 63–84, doi:10.1016/j.precamres.2010.02.022.
[17]
Cahen, L.; Snelling, N.J.; Delhal, J.; Vail, J.R.; Bonhomme, N.; Ledent, D. The Geochronology and Evolution of Africa; Clarendon Press: Oxford, UK, 1984.
[18]
Cahen, L.; Snelling, N.J. The Geochronology of Equatorial Africa; North-Holland Publishing Company: Amsterdam, The Netherlands, 1966.
[19]
Lepersonne, J. Carte géologique du Za？re [in French], Département des Mines, République du Za？re, Royal Museum for Central Africa, Tervuren, Belgium, 1974. 1:2000000.
[20]
Lavreau, J. Le Groupe de la Rusizi (Rusizien du Za？re, Rwanda et Burundi) à la Lumière des Connaissances Actuelles [in French]; Rapport Annuel 1983–1984; Department of Geology and Mineralogy, Royal Museum for Central Africa: Tervuren, Belgium, 1985; pp. 111–119.
[21]
Baudet, D.; Hanon, M.; Lemonne, E.; Theunissen, K. Lithostratigraphie du domaine sédimentaire de la chaine Kibarienne au Rwanda [in French]. Ann. Soc. Géol. Belg. 1988, 112, 225–246.
[22]
Fernandez-Alonso, M.; Cutten, H.; De Waele, B.; Tack, L.; Tahon, A.; Baudet, D.; Barritt, S.D. The Mesoproterozoic Karagwe-Ankole Belt (formerly the NE Kibara Belt): The result of prolonged extensional intracratonic basin development punctuated by two short-lived far-field compressional events. Precambrian Res. 2012, 216–219, 63–86, doi:10.1016/j.precamres.2012.06.007.
[23]
Dewaele, S.; Henjes-Kunst, F.; Melcher, F.; Sitnikova, S.; Burgess, R.; Gerdes, A.; Fernandez, M.A.; De Clercq, F.; Muchez, P.; Lehmann, B. Late Neoproterozoic overprinting of the cassiterite and columbite-tantalite bearing pegmatites of the Gatumba area, Rwanda (Central Africa). J. Afr. Earth Sci. 2011, 61, 10–26, doi:10.1016/j.jafrearsci.2011.04.004.
[24]
Theunissen, K.; Hanon, M.; Fernandez-Alonso, M. Carte Géologique du Rwanda [in French], Service Géologique, Ministère de l’Industrie et de l’Artisanat, République Rwandaise, Tervuren, Belgium, 1991. 1:250000.
[25]
Pohl, W.; Günther, M.A. The origin of Kibaran (late Mid-Proterozoic) tin, tungsten and gold quartz vein deposits in Central Africa: a fluid inclusion study. Miner. Depos. 1991, 26, 51–59.
[26]
Pearce, N.J.G.; Perkins, W.T.; Westgate, J.A.; Gorton, M.P.; Jackson, S.E.; Neal, C.R.; Chenery, S.P. A compilation of new and published major and trace element data for NIST SRM 610 and NIST SRM 612 glass reference materials. Geostand. Newsl. J. Geostand. Geoanal. 1997, 21, 115–144, doi:10.1111/j.1751-908X.1997.tb00538.x.
[27]
Perkins, W.T.; Pearce, N.J.G.; Westgate, J.A. The development of laser ablation ICP-MS and calibration strategies: Examples from the analysis of trace elements in volcanic glass shards and sulfide minerals. Geostand. Newsl. J. Geostand. Geoanal. 1997, 21, 175–190, doi:10.1111/j.1751-908X.1997.tb00669.x.
[28]
Longerich, H.P.; Jackson, S.E.; Günther, D. Laser ablation inductively coupled plasma mass spectrometric transient signal data acquisition and analyte concentration calculation. J. Anal. At. Spectrom. 1996, 11, 899–904, doi:10.1039/ja9961100899.
[29]
Liu, Y.; Hu, Z.; Gao, S.; Günther, D.; Xu, J.; Gao, C.; Chen, H. In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard. Chem. Geol. 2008, 257, 34–43, doi:10.1016/j.chemgeo.2008.08.004.
[30]
Jackson, S.S. Calibration strategies for elemental analysis by LA-ICP-MS. In Laser Ablation ICP-MS in the Earth Sciences: Current Practices and Outstanding Issues, 1st; Sylvester, P., Ed.; Mineralogical Association of Canada: Vancouver, Canada, 2008; Volume 40, pp. 169–188.
[31]
Heinrich, C.A.; Pettke, T.; Halter, W.E.; Aigner-Torres, M.; Audétat, A.; Günther, D.; Hattendorf, B.; Bleiner, D.; Guillong, M.; Horn, I. Quantitative multi-element analysis of minerals, fluid and melt inclusions by laser-ablation inductively-coupled-plasma mass-spectrometry. Geochim. Cosmochim. Acta 2003, 67, 3473–3496, doi:10.1016/S0016-7037(03)00084-X.
[32]
G？bler, H.-E.; Melcher, F.; Graupner, T.; Bahr, A.; Sitnikova, M. A.; Henjes-Kunst, F.; Oberthür, T.; Br？tz, H.; Gerdes, A. Speeding up the analytical workflow for Coltan fingerprinting by an integrated Mineral Liberation Analysis/LA-ICP-MS approach. Geostand. Geoanal. Res. 2011, 35, 431–448, doi:10.1111/j.1751-908X.2011.00110.x.
[33]
Varlamoff, N. Anthoinite, nouveau tungstate hydraté d’alumine [in French]. Ann. Soc. Géol. Belg. 1947, 70, 153–166.
[34]
Van Tassel, R. Ferritungstite et meymacite de Meymac, France, et d’Afrique centrale [in French]. Bull. Soc. Belg. Géol. 1961, 70, 376–406.
[35]
Bertossa, A. Inventaire des minéraux du Rwanda [in French]. Bull. Serv. Géol. Rwanda 1967, 4, 25–45.
[36]
Von Knorring, O.; Sahama, T.G.; Lehtinen, M. Mpororoite, a new secondary tungsten mineral from Uganda. Bull. Geol. Soc. Finl. 1972, 44, 107–110.
[37]
Pohl, W. Géologie de la mine de Bugarama et de ses environs (Rwanda, Afrique) [in French]. Bull. Serv. Géol. Rwanda 1975, 8, 13–42.
[38]
Jedwab, J.; Preat, A. Présence de raspite (PbWO4 MONOCL.) dans l’anthoinite (Al.OH.WO4.H2O TRICL.) de Gifurwe, Rwanda [in French]. Bull. Soc. Belg. Géol. 1979, 88, 185–195.
[39]
Nakashima, K.; Watanabe, M.; Soeda, A. Regional and local variations in the composition of the wolframite series from SW Japan and possible factors controlling compositional variations. Miner. Depos. 1986, 21, 200–206.
[40]
Tindle, A.G.; Webb, P.C. Niobian wolframite from Glen Gairn in the Eastern highlands of Scotland: A microprobe investigation. Geochim. Cosmochim. Acta 1989, 53, 1921–1935, doi:10.1016/0016-7037(89)90313-X.
[41]
Belkasmi, M.; Cuney, M.; Pollard, P.J.; Bastoul, A. Chemistry of the Ta-Nb-Sn-W oxide minerals from the Yichun rare metal granite (SE China): Genetic implications and comparison with Moroccan and French Hercynian examples. Mineral. Mag. 2000, 64, 507–523, doi:10.1180/002646100549391.
[42]
Ferenc, ？; Uher, P. Magnesian wolframite from hydrothermal quartz veins in the Rochovce granite exocontact, Ochtiná, Western Carpathians, Slovakia. Neues Jahrb. Mineral. Abh. 2007, 183, 165–172, doi:10.1127/0077-7757/2007/0066.
[43]
Barkov, A.Y.; Martin, R.F.; Shi, L.; LeBarge, W.; Fedortchouk, Y. Oscillatory zoning in stanniferous hematite and associated W- and Bi-rich minerals from Canadian Creek, Yukon, Canada. Can. Mineral. 2008, 46, 59–72, doi:10.3749/canmin.46.1.59.
[44]
Neiva, A.M.R. Geochemistry of cassiterite and wolframite from tin and tungsten quartz veins in Portugal. Ore Geol. Rev. 2008, 33, 221–238, doi:10.1016/j.oregeorev.2006.05.013.
[45]
Mignardi, S.; Ferrini, V.; Masi, U.; Nabais, L.C.; de Sousa Bernardo, M. Significance of the Major- and Trace-Element Contents of Wolframite from the Deposits of Panasqueira and Vale de Gatas, Portugal. In Proceedings of the Ninth Quadrennial IAGOD Symposium, Beijing, China, 12–18 August 1994; Hagni, R.D., Ed.; Schweizerbart: Stuttgart, Germany, 1998;; pp. 475–484.
[46]
Goldmann, S. Mineralogical-Geochemical Characterisation of Cassiterite and Wolframite for an Analytical Fingerprint of Ore Concentrates (Provisional Title). Ph.D. Thesis, Leibniz University Hannover, Hannover, Germany. ongoing.
[47]
McDonough, W.; Sun, S.S. The composition of the earth. Chem. Geol. 1995, 120, 223–253, doi:10.1016/0009-2541(94)00140-4.
[48]
Ghaderi, M.; Palin, J.M.; Campbell, I.H.; Sylvester, P.J. Rare earth element systematics in scheelite from hydrothermal gold deposits in the Kalgoorlie-Norseman Region, Western Australia. Econ. Geol. 1999, 94, 423–438, doi:10.2113/gsecongeo.94.3.423.
[49]
Dostal, J.; Kontak, D.J.; Chatterjee, A.K. Trace element geochemistry of scheelite and rutile from metaturbidite-hosted quartz vein gold deposits, Meguma Terrane, Nova Scotia, Canada: Genetic implications. Mineral. Pet. 2009, 97, 95–109, doi:10.1007/s00710-009-0067-0.
[50]
Wood, S.A.; Samson, I.M. The hydrothermal geochemistry of tungsten in granitoid environments: I. Relative solubilities of ferberite and scheelite as a function of T, P, pH, and mNaCl. Econ. Geol. 2000, 95, 143–182, doi:10.2113/gsecongeo.95.1.143.
[51]
Robie, R.A.; Bethke, P.M; Beardsley, K.K. Selected X-Ray Crystallographic Data, Molar Volumes, and Densities of Minerals and Related Substances; U.S. Geological Survey Bulletin 1248; U.S; Government Printing Office: Washington, DC, USA, 1967.
[52]
Kuzmin, A.; Purans, J. Local atomic and electronic structure of tungsten ions in AWO4 crystals of scheelite and wolframite types. Radiat. Meas. 2001, 33, 583–586, doi:10.1016/S1350-4487(01)00063-4.
[53]
Shannon, R.D. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallogr. Sect. A Found. Crystallogr. 1976, 32, 751–767, doi:10.1107/S0567739476001551.
[54]
Hazen, R.M.; Finger, L.W.; Mariathasan, J.W.E. High-pressure crystal chemistry of scheelite-type tungstates and molybdates. J. Phys. Chem. Solids 1985, 46, 253–263, doi:10.1016/0022-3697(85)90039-3.
[55]
Macavei, J.; Schulz, H. The crystal structure of wolframite type tungstates at high pressure. Z. Krist. 1993, 207, 193–208, doi:10.1524/zkri.1993.207.Part-2.193.
[56]
Grubb, P.L.C. Solid solution relationships between wolframite and scheelite. Am. Mineral. 1967, 52, 418–426.
[57]
Roberts, S.; Palmer, M.R.; Waller, L. Sm-Nd and REE characteristics of tourmaline and scheelite from the Bj？rkdal gold deposit, Northern Sweden: evidence of an intrusion-related gold deposit? Econ. Geol. 2006, 101, 1415–1425, doi:10.2113/gsecongeo.101.7.1415.
[58]
Brugger, J.; Lahaye, Y.; Costa, S.; Lambert, D.; Bateman, R. Inhomogeneous distribution of REE in scheelite and dynamics of Archaean hydrothermal systems (Mt. Charlotte and Drysdale gold deposits, Western Australia). Contrib. Mineral. Petrol. 2000, 139, 251–264, doi:10.1007/s004100000135.
[59]
Uspensky, E.; Brugger, J.; Graeser, S. REE geochemistry systematics of scheelite from the Alps using luminescence spectroscopy: From global regularities to local control. Schweiz. Mineral. Petrogr. Mitt. 1998, 78, 31–54.
