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The new mineral species r&uuml, dlingerite, ideally Mn2+2V5+As5+O7&middot, 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. R&uuml, dlingerite 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 &mu, m in length. Electron-microprobe analysis of r&uuml, dlingerite 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 r&uuml, dlingerite is Mn1.97(V5+1.17 As0.83Si0.01)&Sigma, 2.01O7&middot, 2H2O. The main diffraction lines are [dobs in &Aring, (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) &Aring, b = 14.5673(4) &Aring, c = 6.7011(2) &Aring, &beta, = 93.773(2)&deg, V = 762.58(4) &Aring, 3, Z = 4. The crystal structure has been solved and refined to R1 = 0.041 on the basis of 3784 reflections with Fo &gt, 4&sigma, (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 R&uuml, dlinger (born 1919), a pioneer in the 1960&ndash, 1980s, in the search and study of the small minerals from the Alpine manganese mineral deposits of Grisons.

The information given here is provided by the IMA Commission on New Minerals, Nomenclature and Classification for comparative purposes and as a service to mineralogists working on new species. Each mineral is described in the following format: Mineral name, if the authors agree on its release prior to the full description appearing in press Chemical formula Type locality Full authorship of proposal E-mail address of corresponding author Relationship to other minerals Crystal system, Space group; Structure determined, yes or no Unit-cell parameters Strongest lines in the powder X-ray diffraction pattern Type specimen repository and specimen number Citation details for the mineral prior to publication of full description Citation details concern the fact that this information will be published in the Mineralogical Magazine on a routine basis, as well as being added month by month to the Commission's web site. It is still a requirement for the authors to publish a full description of the new mineral. NO OTHER INFORMATION WILL BE RELEASED BY THE COMMISSION IMA No. 2016-083 Potassic-magnesio-arfvedsonite KNa2Mg4Fe3+Si8O22(OH)2 Buhovo-Seslavtsi pluton, Sofia district, Bulgaria (42°47′N, 23°34′E) Momchil Dyulgerov*, Bernard Platevoet, Roberta Oberti, Milen Kadiyski and Ventsislav Rusanov *E-mail: momchil@gea.uni-sofia.bg Amphibole supergroup Monoclinic: C 2/ m ; structure determined a = 9.986(2), b = 18.022(3), c = 5.3151(12) A, β = 104.44(2)° 8.519(87), 3.406(82), 3.172(72), 2.755(59), 2.716(100), 2.594(52), 2.551(68), 2.175(57) Type material is deposited in the collections of the Museum of Mineralogy, Petrology and Economic Geology, Sofia University ‘St. Kliment Ohridski’, 15 Tsar Osvoboditel Blvd, Sofia 1504, Bulgaria, catalogue number M 7661 How to cite: Dyulgerov, M., Platevoet, B., Oberti, R., Kadiyski, M. and Rusanov, V. (2017) Potassic-magnesio-arfvedsonite, IMA 2016-083. CNMNC Newsletter No. 35, February 2017, page 210; Mineralogical Magazine , 81 , 209–213. IMA No. 2016-084 Kampelite Ba6Mg3Sc8 …

Despite the particular scientific interest in the elements with high affinity to S and O2, but found in zero-valence state in nature, the origin of these native minerals has been little explored and remains obscure. Here we describe unique Sn-Pb droplets found in a closed analcime-calcite amygdale collected from a basaltic unit cropping out at Carsaig Bay (Isle of Mull, Inner Hebrides). The droplets consist of intimate intergrowths of nearly pure Sn0 and Pb0 domains in proportion 88:12 and are enveloped in a thin, brownish, amber-like film of organic composition, which gives the impression of metallic “embryos” in organic “placenta”. The occurrence of the Sn-Pb droplets in a closed amygdale, their relationship with the host analcime+calcite and their Pb isotope composition (which does not match any known anthropogenic Pb source) rule out the possibility of anthropogenic contamination and support the natural origin of the Sn-Pb alloy. The variable isotope (Pb, Sr, Nd) compositions in different members of the host basaltic sequence suggest that a parent basaltic magma was modified by crustal assimilation and post-emplacement alteration processes. Considering all possible scenarios, it appears that the most likely source of Pb for the Sn-Pb alloy is a discrete basaltic unit with an isotopic composition comparable to the Antrim basalts (Northern Ireland). The amygdale phases, on the other hand, show isotopic evidence for incorporation of elements from both local basaltic and sedimentary units. The apparent isotopic disequilibrium between Sn-Pb droplets and amygdale phases indicates a complex, multi-stage fluid evolution. The occurrence of Sn-Pb droplets in organic capsules suggests that the droplets and the enveloping organic substances are co-precipitates. This implies that the transportation and deposition of Sn and Pb might have occurred through organometallic compounds. We assume interaction of seawater fluids carrying metals leached from basaltic rocks with hydrocarbons from sedimentary units as a prerequisite for the formation of the organometallic complexes. The zeolites lining the basaltic vesicles might have destabilized the migrating organo- Sn and Pb compounds causing their breakdown and precipitation of Sn-Pb alloy.

Godkänd; 2007; 20110704 (andbra)