Abstract

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 triva-lent 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+.

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