New occurrences of willemite-franklinite assemblages in Bergslagen, central Sweden
European Journal of Mineralogy Volume 14 Number 3 (2002), p. 621 - 626
published: Jun 5, 2002
ArtNo. ESP147051403017, Price: 29.00 €
Two new occurrences of willemite coexisting with franklinite are described from the Bergslagen region. At the Garpenberg Norra Pb-Zn mine (Hedemora, Dalarna) willemite and franklinite occur in silicate skarn rocks in association with clino-amphibole, phlogopite, quartz, galena, sphalerite, fluorite and barite. At the Hasselhöjden metacarbonate quarry (Hällefors, Örebro) the two minerals appear with mainly sphalerite in talc-bearing dolomite marble. Based on electron-microprobe (EMP) analyses, willemite from Garpenberg Norra contains 0.4-2.1 MnO, 0.2-1.5 MgO and 0.1-1.2 Fe2O3, whereas at Hasselhöjden the mineral has 0.4 Fe2O3 as the main impurity (all in wt.%). Mössbauer spectroscopy and EMP data show that Fe is dominantly trivalent and to some extent substitutes for Si in these willemite samples. Franklinite from Hasselhöjden contains up to 7.6 wt.% V2O5, incorporated according to the substitution 2 (Zn, Fe)2+ + V5+ = 3 Fe3+.