Reference:
▪ Škoda, R., Plášil, J., Čopjaková, R., Novák, M., Jonsson, E., Vašinová Galiová, M., , Holtstam, D. (2018): Gadolinite-(Nd), a new member of the gadolinite supergroup from Fe-REE deposits of Bastnäs-type, Sweden. Mineralogical Magazine, 82, S133–S145.
Abstract:
A new member of the gadolinite supergroup, mineral gadolinite-(Nd), IMA2016-013, ideally Nd2FeBe2Si2O10, was found in the Malmkärra mine, ~3.5 km WSW of Norberg, south-central Sweden, where it occurs in association with fluorbritholite-(Ce), västmanlandite-(Ce), dollaseite-(Ce) bastnäsite-(Ce) and tremolite. Gadolinite-(Nd) forms anhedral grains up to 150 μm in size, commonly occurring as aggregates of olive green colour. Crystals are transparent with vitreous to adamantine lustre. Gadolinite-(Nd) is brittle with conchoidal fracture, no cleavage or parting was observed. It has a white streak, the Mohs hardness is 6.5-7 and the calculated density is 4.86 g/cm3. Optically, the mineral is weakly pleochroic in shades of olive green, biaxial (-), nα = 1.78(1), nβ(calc.) = 1.80, nγ = 1.81(1) measured in white light, 2V(meas.) = 62 (3)º. Electronmicroprobe and LA-ICP-MS analysis [in wt.%] provided SiO2 21.77, Y2O3 5.49, La2O3 2.78, Ce2O3 14.04, Pr2O3 3.28, Nd2O3 19.27, Sm2O3 5.30, Eu2O3 0.24, Gd2O3 4.10, Tb2O3 0.36, Dy2O3 1.32, Ho2O3 0.18, Er2O3 0.38, MgO 0.51, CaO 0.14, MnO 0.10, FeO 10.62, B2O3 0.10, BeOcalc. 8.99, H2Ocalc. 0.55, and total 99.52 giving following empirical formula (based on 2 Si): (Nd0.632Ce0.472Y0.268Sm0.168Gd0.125Pr0.110La0.094Dy0.039Ca0.014Er0.011Tb0.011Eu0.008Ho0.008)Σ1.957(Fe0.81 6Mg0.070Mn0.008)Σ0.894(Be1.984B0.016) Σ2.000Si2O9.660OH0.337. A weak Raman vibration band at ~ 3525 cm-1 confirms the presence of water in the structure. Gadolinite-(Nd) is monoclinic, P21/c, with a = 4.8216(3) Å, b = 7.6985(4) Å, c = 10.1362(6) Å, β = 90.234(4)°, V = 376.24(6) Å3 and Z = 2. The strongest X-ray diffraction lines are [dobs in Å (hkl) Irel]: 4.830 (100) 72, 3.603 (021) 37, 3.191(-112) 52, 3.098 (013) 35, 2.888 (121) 100, 2.607(113) 49, 2.412 (200) 24. Besides the Malmkärra mine, gadolinite-(Nd) was also recorded also at Johannagruvan and Nya Bastnäs. Minerals of the gadolinite subgroup together with britholite-(Ce) incorporate the highest fraction of medium to heavy REE among associated REE minerals at Malmkärra mine and possibly in all Bastnäs-type deposits.
▪ Škoda, R., Plášil, J., Čopjaková, R., Novák, M., Jonsson, E., Vašinová Galiová, M., , Holtstam, D. (2018): Gadolinite-(Nd), a new member of the gadolinite supergroup from Fe-REE deposits of Bastnäs-type, Sweden. Mineralogical Magazine, 82, S133–S145.
Abstract:
A new member of the gadolinite supergroup, mineral gadolinite-(Nd), IMA2016-013, ideally Nd2FeBe2Si2O10, was found in the Malmkärra mine, ~3.5 km WSW of Norberg, south-central Sweden, where it occurs in association with fluorbritholite-(Ce), västmanlandite-(Ce), dollaseite-(Ce) bastnäsite-(Ce) and tremolite. Gadolinite-(Nd) forms anhedral grains up to 150 μm in size, commonly occurring as aggregates of olive green colour. Crystals are transparent with vitreous to adamantine lustre. Gadolinite-(Nd) is brittle with conchoidal fracture, no cleavage or parting was observed. It has a white streak, the Mohs hardness is 6.5-7 and the calculated density is 4.86 g/cm3. Optically, the mineral is weakly pleochroic in shades of olive green, biaxial (-), nα = 1.78(1), nβ(calc.) = 1.80, nγ = 1.81(1) measured in white light, 2V(meas.) = 62 (3)º. Electronmicroprobe and LA-ICP-MS analysis [in wt.%] provided SiO2 21.77, Y2O3 5.49, La2O3 2.78, Ce2O3 14.04, Pr2O3 3.28, Nd2O3 19.27, Sm2O3 5.30, Eu2O3 0.24, Gd2O3 4.10, Tb2O3 0.36, Dy2O3 1.32, Ho2O3 0.18, Er2O3 0.38, MgO 0.51, CaO 0.14, MnO 0.10, FeO 10.62, B2O3 0.10, BeOcalc. 8.99, H2Ocalc. 0.55, and total 99.52 giving following empirical formula (based on 2 Si): (Nd0.632Ce0.472Y0.268Sm0.168Gd0.125Pr0.110La0.094Dy0.039Ca0.014Er0.011Tb0.011Eu0.008Ho0.008)Σ1.957(Fe0.81 6Mg0.070Mn0.008)Σ0.894(Be1.984B0.016) Σ2.000Si2O9.660OH0.337. A weak Raman vibration band at ~ 3525 cm-1 confirms the presence of water in the structure. Gadolinite-(Nd) is monoclinic, P21/c, with a = 4.8216(3) Å, b = 7.6985(4) Å, c = 10.1362(6) Å, β = 90.234(4)°, V = 376.24(6) Å3 and Z = 2. The strongest X-ray diffraction lines are [dobs in Å (hkl) Irel]: 4.830 (100) 72, 3.603 (021) 37, 3.191(-112) 52, 3.098 (013) 35, 2.888 (121) 100, 2.607(113) 49, 2.412 (200) 24. Besides the Malmkärra mine, gadolinite-(Nd) was also recorded also at Johannagruvan and Nya Bastnäs. Minerals of the gadolinite subgroup together with britholite-(Ce) incorporate the highest fraction of medium to heavy REE among associated REE minerals at Malmkärra mine and possibly in all Bastnäs-type deposits.