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Manganiakasakaite-(La) and Ferriakasakaite-(Ce), Two New Epidote Supergroup Minerals from Piedmont, Italy

1
Dipartimento di Scienze della Terra, Università di Pisa, Via Santa Maria 53, I-56126 Pisa, Italy
2
Dipartimento di Scienze della Terra, Università di Firenze, Via G. La Pira 4, I-50132 Firenze, Italy
3
Department of Applied Geological Sciences and Geophysics, University of Leoben, Peter Tunner Str. 5, A-8700 Leoben, Austria
4
Associazione Micromineralogica Italiana, Via Luigi Delfino 74, I-17017 Millesimo (SV), Italy
5
Associazione Micromineralogica Italiana, Via Montenotte 18/6, I-17100 Savona, Italy
6
Associazione Micromineralogica Italiana, Via San Pietro 55, I-10073 Devesi-Ciriè (TO), Italy
*
Author to whom correspondence should be addressed.
Minerals 2019, 9(6), 353; https://doi.org/10.3390/min9060353
Received: 20 May 2019 / Revised: 6 June 2019 / Accepted: 7 June 2019 / Published: 9 June 2019
(This article belongs to the Collection New Minerals)
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Abstract

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)Al1.00 M(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)(Ce0.37La0.17Nd0.06Pr0.03Ca0.350.02) M(1)(Fe3+0.61Al0.39) M(2)Al1.00 M(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. View Full-Text
Keywords: manganiakasakaite-(La); ferriakasakaite-(Ce); epidote supergroup; allanite group; new mineral; Monte Maniglia; Piedmont; Italy manganiakasakaite-(La); ferriakasakaite-(Ce); epidote supergroup; allanite group; new mineral; Monte Maniglia; Piedmont; Italy
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Biagioni, C.; Bonazzi, P.; Pasero, M.; Zaccarini, F.; Balestra, C.; Bracco, R.; Ciriotti, M.E. Manganiakasakaite-(La) and Ferriakasakaite-(Ce), Two New Epidote Supergroup Minerals from Piedmont, Italy. Minerals 2019, 9, 353.

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