ALBERT

Description: Leószilárdite (IMA2015-128), Na 6 Mg(UO 2 ) 2 (CO 3 ) 6 ·6H 2 O, was found in the Markey Mine, Red Canyon, White Canyon District, San Juan County, Utah, USA, in areas with abundant andersonite, natrozippeite, gypsum, anhydrite, and probable hydromagnesite along with other secondary uranium minerals bayleyite, čejkaite and johannite. The new mineral occurs as aggregates of pale yellow bladed crystals flattened on {001} and elongated along [010], individually reaching up to 0.2 mm long. More commonly it occurs as pale yellow pearlescent masses to 2 mm consisting of very small plates. Leószilárdite fluoresces green under both longwave and shortwave ultraviolet light, and is translucent with a white streak, hardness of 2 (Mohs), and brittle tenacity with uneven fracture. The new mineral is readily soluble in room temperature H 2 O. Crystals have perfect cleavage along {001}, and exhibit the forms {110}, {001}, {100}, {101} and { 1 01}. Optically, leószilárdite is biaxial (–), α = 1.504(1), β = 1.597(1), = 1.628(1) (white light); 2V (meas.) = 57(1)°, 2V (calc.) = 57.1°; dispersion r 〉 v , slight. Pleochroism: X = colourless, Y and Z = light yellow; X 〈 Y Z . The average of six wavelength dispersive spectroscopic analyses provided Na 2 O 14.54, MgO 3.05, UO 3 47.95, CO 2 22.13, H 2 O 9.51, total 97.18 wt.%. The empirical formula is Na 5.60 Mg 0.90 U 2 O 28 C 6 H 12.60 , based on 28 O apfu. Leószilárdite is monoclinic, C 2 /m , a = 11.6093(21), b = 6.7843(13), c = 15.1058(28) Å, β = 91.378(3)°, V = 1189.4(4) Å 3 and Z = 2. The crystal structure ( R 1 = 0.0387 for 1394 reflections with I obs 〉 4 I ), consists of uranyl tricarbonate anion clusters [(UO 2 )(CO 3 ) 3 ] 4– held together in part by irregular chains of NaO 5 (H 2 O) polyhedra sub parallel to [010]. Individual uranyl tricarbonate clusters are also linked together by three-octahedron units consisting of two Na-centred octahedra that share the opposite faces of a Mg-centred octahedron at the centre (Na–Mg–Na), and have the composition Na 2 MgO 12 (H 2 O) 4 . The name of the new mineral honours the Hungarian-American physicist, inventor and biologist Dr. Leó Szilárd (1898–1964).

Description: Leószilárdite (IMA2015-128), Na 6 Mg(UO 2 ) 2 (CO 3 ) 6 ·6H 2 O, was found in the Markey Mine, Red Canyon, White Canyon District, San Juan County, Utah, USA, in areas with abundant andersonite, natrozippeite, gypsum, anhydrite, and probable hydromagnesite along with other secondary uranium minerals bayleyite, čejkaite and johannite. The new mineral occurs as aggregates of pale yellow bladed crystals flattened on {001} and elongated along [010], individually reaching up to 0.2 mm long. More commonly it occurs as pale yellow pearlescent masses to 2 mm consisting of very small plates. Leószilárdite fluoresces green under both longwave and shortwave ultraviolet light, and is translucent with a white streak, hardness of 2 (Mohs), and brittle tenacity with uneven fracture. The new mineral is readily soluble in room temperature H 2 O. Crystals have perfect cleavage along {001}, and exhibit the forms {110}, {001}, {100}, {101} and { 1 01}. Optically, leószilárdite is biaxial (–), α = 1.504(1), β = 1.597(1), = 1.628(1) (white light); 2V (meas.) = 57(1)°, 2V (calc.) = 57.1°; dispersion r 〉 v , slight. Pleochroism: X = colourless, Y and Z = light yellow; X 〈 Y Z . The average of six wavelength dispersive spectroscopic analyses provided Na 2 O 14.54, MgO 3.05, UO 3 47.95, CO 2 22.13, H 2 O 9.51, total 97.18 wt.%. The empirical formula is Na 5.60 Mg 0.90 U 2 O 28 C 6 H 12.60 , based on 28 O apfu. Leószilárdite is monoclinic, C 2 /m , a = 11.6093(21), b = 6.7843(13), c = 15.1058(28) Å, β = 91.378(3)°, V = 1189.4(4) Å 3 and Z = 2. The crystal structure ( R 1 = 0.0387 for 1394 reflections with I obs 〉 4 I ), consists of uranyl tricarbonate anion clusters [(UO 2 )(CO 3 ) 3 ] 4– held together in part by irregular chains of NaO 5 (H 2 O) polyhedra sub parallel to [010]. Individual uranyl tricarbonate clusters are also linked together by three-octahedron units consisting of two Na-centred octahedra that share the opposite faces of a Mg-centred octahedron at the centre (Na–Mg–Na), and have the composition Na 2 MgO 12 (H 2 O) 4 . The name of the new mineral honours the Hungarian-American physicist, inventor and biologist Dr. Leó Szilárd (1898–1964).

Description: Surveys have revealed many multi-planet systems containing super-Earths and Neptunes in orbits of a few days to a few months. There is debate whether in situ assembly or inward migration is the dominant mechanism of the formation of such planetary systems. Simulations suggest that migration creates tightly packed systems with planets whose orbital periods may be expressed as ratios of small integers (resonances), often in a many-planet series (chain). In the hundreds of multi-planet systems of sub-Neptunes, more planet pairs are observed near resonances than would generally be expected, but no individual system has hitherto been identified that must have been formed by migration. Proximity to resonance enables the detection of planets perturbing each other. Here we report transit timing variations of the four planets in the Kepler-223 system, model these variations as resonant-angle librations, and compute the long-term stability of the resonant chain. The architecture of Kepler-223 is too finely tuned to have been formed by scattering, and our numerical simulations demonstrate that its properties are natural outcomes of the migration hypothesis. Similar systems could be destabilized by any of several mechanisms, contributing to the observed orbital-period distribution, where many planets are not in resonances. Planetesimal interactions in particular are thought to be responsible for establishing the current orbits of the four giant planets in the Solar System by disrupting a theoretical initial resonant chain similar to that observed in Kepler-223.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Mills, Sean M -- Fabrycky, Daniel C -- Migaszewski, Cezary -- Ford, Eric B -- Petigura, Erik -- Isaacson, Howard -- England -- Nature. 2016 May 11;533(7604):509-12. doi: 10.1038/nature17445.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, Illinois 60637, USA. ; Institute of Physics and CASA*, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland. ; Torun Centre for Astronomy, Nicolaus Copernicus University, Gagarina 11, 87-100 Torun, Poland. ; Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. ; Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. ; Center for Astrostatistics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. ; University of California at Berkeley, Berkeley, California 94720, USA. ; California Institute of Technology, Pasadena, California 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27225123" target="_blank"〉PubMed〈/a〉

Description: The new mineral species braccoite, ideally Na $${\mathrm{Mn}}_{5}^{2+}$$ [Si 5 AsO 17 (OH)](OH), has been discovered in the Valletta mine dumps, in Maira Valley, Cuneo province, Piedmont, Italy. Its origin is probably related to the reaction between ore minerals and hydrothermal fluids. It occurs as subhedral crystals in brown-red coloured thin masses, with a pale-yellow streak and vitreous to resinous lustre. Braccoite is associated with tiragalloite, for which new data are provided, as well as gamagarite, hematite, manganberzeliite, palenzonaite, quartz, saneroite, tokyoite, unidentified Mn oxides, organic compounds, and Mn arsenates and silicates under study. Braccoite is biaxial positive with refractive indices α = 1.749(1), β = 1.750(1), = 1.760(1). It is triclinic, space group P 1I, with a = 9.7354(4), b = 9.9572(3), c = 9.0657(3) Å, α = 92.691(2), β = 117.057(4), = 105.323(3)°, V = 740.37(4) Å 3 and Z = 2. Its calculated density is 3.56 g/cm 3 . The ten strongest diffraction lines of the observed powder X-ray diffraction (XRD) pattern are [ d in Å, ( I ), ( hkl )]: 3.055 (69)(22I1), 3.042 (43)(102), 3.012 (65)(32I1I), 2.985 (55)(23I1I), 2.825 (100)(213I), 2.708 (92)(220), 2.627 (43)(23I2I), 2.381 (58)(41I1I), 2.226 (25)(214I) and 1.680 (433I)(36). Chemical analyses by wavelength-dispersive spectroscopy electron microprobe gave (wt.%): Na 2 O 4.06, CaO 0.05, MnO 41.76, MgO 0.96, Al 2 O 3 0.04, CuO 0.02, SiO 2 39.73, As 2 O 5 6.87, V 2 O 5 1.43, SO 3 0.01 and F 0.04. H 2 O 2.20 was calculated on the basis of 2OH groups p.f.u. Raman spectroscopy confirmed the presence of (SiO 4 ) 4– , (AsO 4 ) 3– and OH groups. The empirical formula, calculated on the basis of cations-(Na,K) = 11 p.f.u., in agreement with the results of the crystal structure, is Na 1.06 ( $${\mathrm{Mn}}_{4.46}^{2+}$$ $${\mathrm{Mn}}_{0.32}^{3+}$$ Mg 0.19 $${\mathrm{V}}_{0.01}^{3+}$$ Al 0.01 Ca 0.01 )[Si 5 (As 0.48 Si 0.37 $${\mathrm{V}}_{0.15}^{5+}$$ )O 17 (OH)](OH 0.98 F 0.02 ); the simplified formula is Na(Mn,Mg,Al,Ca) 5 [Si 5 (As,V,Si)O 17 (OH)](OH,F). Single-crystal XRD allowed the structure to be solved by direct methods and revealed that braccoite is the As-dominant analogue of saneroite. The structure model was refined on the basis of 4389 observed reflections to R 1 = 3.47%. Braccoite is named in honour of Dr Roberto Bracco (b. 1959), a systematic minerals collector with a special interest in manganese minerals. The new mineral was approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (IMA 2013-093).

Description: 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.