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The new mineral species rüdlingerite, ideally Mn2+2V5+As5+O7·2H2O, occurs in the Fianel mine, in Val Ferrera, Grisons, Switzerland, a small Alpine metamorphic Mn deposit. It is associated with ansermetite and Fe oxyhydroxide in thin fractures in Triassic dolomitic marbles. Rüdlingerite was also found in specimens recovered from the dump of the Valletta mine, Canosio, Cuneo, Piedmont, Italy, where it occurs together with massive braccoite and several other As- and V-rich phases in richly mineralized veins crossing the quartz-hematite ore. The new mineral displays at both localities yellow to orange, flattened elongated prismatic, euhedral crystals measuring up to 300 μm in length. Electron-microprobe analysis of rüdlingerite from Fianel gave (in wt%): MnO 36.84, FeO 0.06, As2O5, 25.32, V2O5 28.05, SiO2 0.13, H2Ocalc 9.51, total 99.91. On the basis of 9 O anions per formula unit, the chemical formula of rüdlingerite is Mn1.97(V5+1.17 As0.83Si0.01)Σ2.01O7·2H2O. The main diffraction lines are [dobs in Å (Iobs) hkl]: 3.048 (100) 022, 5.34 (80) 120, 2.730 (60) 231, 2.206 (60) 16-1, 7.28 (50) 020, 2.344 (50) 250, 6.88 (40) 110, and 2.452 (40) 320. Study of the crystal structure showcases a monoclinic unit cell, space group P21/n, with a = 7.8289(2) Å, b = 14.5673(4) Å, c = 6.7011(2) Å, β = 93.773(2)°, V = 762.58(4) Å3, Z = 4. The crystal structure has been solved and refined to R1 = 0.041 on the basis of 3784 reflections with Fo > 4σ(F). It shows Mn2+ hosted in chains of octahedra that are subparallel to [-101] and bound together by pairs of tetrahedra hosted by V5+ and As5+, building up a framework. Additional linkage is provided by hydrogen-bonding through H2O coordinating Mn2+ at the octahedra. One tetrahedrally coordinated site is dominated by V5+, T(1)(V0.88As0.12), corresponding to an observed site scattering of 24.20 electrons per site (eps), whereas the second site is strongly dominated by As5+,T(2)(As0.74V0.26), with, accordingly, a higher observed site scattering of 30.40 eps. The new mineral has been approved by the IMA-CNMNC and named for Gottfried Rüdlinger (born 1919), a pioneer in the 1960–1980s, in the search and study of the small minerals from the Alpine manganese mineral deposits of Grisons. [ABSTRACT FROM AUTHOR]

Two new monoclinic (P21/m) epidote supergroup minerals manganiakasakaite-(La) and ferriakasakaite-(Ce) were found in the small Mn ore deposit of Monte Maniglia, Bellino, Varaita Valley, Cuneo Province, Piedmont, Italy. Manganiakasakaite-(La) occurs as subhedral grains embedded in pyroxmangite. Its empirical formula is A(1)(Ca0.62Mn2+0.38) A(2)(La0.52Nd0.08Pr0.07Ce0.07Y0.01Ca0.25) M(1)(Mn3+0.52Fe3+0.28Al0.18V3+0.01) M(2)Al1.00M(3)(Mn2+0.60Mn3+0.27Mg0.13) T(1−3)(Si2.99Al0.01) O12 (OH), corresponding to the end-member formula CaLaMn3+AlMn2+(Si2O7)(SiO4)O(OH). Unit-cell parameters are a = 8.9057(10), b = 5.7294(6), c = 10.1134(11) Å, β = 113.713(5)°, V = 472.46(9) Å3, Z = 2. The crystal structure of manganiakasakaite-(La) was refined to a final R1 = 0.0262 for 2119 reflections with Fo > 4σ(Fo) and 125 refined parameters. Ferriakasakaite-(Ce) occurs as small homogeneous domains within strongly inhomogeneous prismatic crystals, where other epidote supergroup minerals coexist [manganiandrosite-(Ce), "androsite-(Ce)", and epidote]. Associated minerals are calcite and hematite. Its empirical formula is A(1)(Ca0.64Mn2+0.36) A(2)(Ce0.37La0.17Nd0.06Pr0.03Ca0.35□0.02) M(1)(Fe3+0.61Al0.39) M(2)Al1.00M(3)(Mn2+0.64Mn3+0.33Fe3+0.02Mg0.01) T(1−3)Si3.01 O12 (OH), the end-member formula being CaCeFe3+AlMn2+(Si2O7)(SiO4)O(OH). Unit-cell parameters are a = 8.9033(3), b = 5.7066(2), c = 10.1363(3) Å, β = 114.222(2)°, V = 469.66(3) Å3, Z = 2. The crystal structure of ferriakasakaite-(Ce) was refined to a final R1 = 0.0196 for 1960 unique reflections with Fo > 4σ(Fo) and 124 refined parameters. [ABSTRACT FROM AUTHOR]