ALBERT

Description: Zoned crystals of carbocernaite occur in hydrothermally reworked burbankite-fluorapatite-bearing calcite carbonatite at Bear Lodge, Wyoming. The mineral is paragenetically associated with pyrite, strontianite, barite, ancylite-(Ce), and late-stage calcite, and is interpreted to have precipitated from sulfate-bearing fluids derived from an external source and enriched in Na, Ca, Sr, Ba, and rare-earth elements (REE) through dissolution of the primary calcite and burbankite. The crystals of carbocernaite show a complex juxtaposition of core-rim, sectoral, and oscillatory zoning patterns arising from significant variations in the content of all major cations, which can be expressed by the empirical formula (Ca 0.43–0.91 Sr 0.40–0.69 REE 0.18–0.59 Na 0.18–0.53 Ba 0–0.08 ) 1.96–2.00 (CO 3 ) 2 . Interelement correlations indicate that the examined crystals can be viewed as a solid solution between two hypothetical end-members, CaSr(CO 3 ) 2 and NaREE(CO 3 ) 2 , with the most Na-REE-rich areas in pyramidal (morphologically speaking) growth sectors representing a probable new mineral species. Although the Bear Lodge carbocernaite is consistently enriched in light REE relative to heavy REE and Y (chondrite-normalized La/Er = 500–4200), the pyramidal sectors exhibit a greater degree of fractionation between these two groups of elements relative to their associated prismatic sectors. A sample approaching the solid-solution midline [(Ca 0.57 Na 0.42 ) 0.99 (Sr 0.50 REE 0.47 Ba 0.01 ) 0.98 (CO 3 ) 2 ] was studied by single-crystal X-ray diffraction and shown to have a monoclinic symmetry [space group P 11 m , a = 6.434(4), b = 7.266(5), c = 5.220(3) Å, = 89.979(17)°, Z = 2] as opposed to the orthorhombic symmetry (space group Pb 2 1 m ) proposed in earlier studies. The symmetry reduction is due to partial cation order in sevenfold-coordinated sites occupied predominantly by Ca and Na, and in tenfold-coordinated sites hosting Sr, REE, and Ba. The ordering also causes splitting of carbonate vibrational modes at 690–740 and 1080–1100 cm –1 in Raman spectra. Using Raman micro-spectroscopy, carbocernaite can be readily distinguished from burbankite- and ancylite-group carbonates characterized by similar energy-dispersive spectra.

Description: Hydroxylgugiaite, ideally (Ca 3 1 ) 4 (Si 3.5 Be 2.5 ) 6 O 11 (OH) 3 , is a new mineral species from two localities in the Larvik plutonic complex in Porsgrunn, Telemark, Norway, and one locality in Ilímaussaq, Greenland. Hydroxylgugiaite crystals occur as squat dipyramids {111} (30 x 50 μm) or as elongate tetragonal prisms. The crystals are translucent, white to pale grey in color, with a white streak and vitreous luster. It is brittle, with no apparent cleavage. Hydroxylgugiaite is uniaxial positive with = 1.622 ± 0.002 and = 1.632 ± 0.002. There is no pleochroism and birefringence is low. The average of eight analyses of a single grain of type material (oxide wt.%) gave Na 2 O 2.04, CaO 32.90, FeO 0.22, MnO 0.74, BeO 13.47 (LA-ICP-MS), Al 2 O 3 0.74, SiO 2 44.06, F 1.74, H 2 O (assuming 3 OH + F) 4.93, Total (–0.73 O = F) 100.10. Potassium, strontium, and magnesium were measured but not detected. The calculated density is 2.79 g cm –3 . The empirical formula on the basis of 14 anions including 3 OH – + F – is: (Ca 2.76 Na 0.31 Mn 0.05 Fe 0.01 ) 3.13 (Si 3.45 Be 2.53 Al 0.07 ) 6.05 O 11 [(OH) 2.57 F 0.43 ] 3 . The formula from crystal-structure analysis of the Saga specimen is: (Ca 3.02 0.98 ) 4 (Si 1.79 Be 0.21 ) 2 (Be 2.29 Si 1.71 ) 4 O 11 (OH) 3 . Combined structural and chemical data gives the following formula for the Nakkaalaaq specimen: (Ca 2.88 0.98 Na 0.12 Mn 0.02 ) 4 (Si 1.80 Be 0.17 Al 0.03 ) 2 (Be 2.32 Si 1.68 ) 4 O 11 [(OH) 2.70 F 0.30 ] 3 ; with simplified formula (Ca,) 4 (Si,Be) 2 (Be,Si) 4 O 11 (OH) 3 . The crystal structure of hydroxylgugiaite is tetragonal in acentric space group P 2 1 / m , with a 7.4151(2), b 7.4151, c 4.9652(1) Å, V 272.9(1) Å 3 , and Z = 1. It has been refined to an R index of 0.028 on the basis of 342 observed reflections and a correction for the {110} twin law. It is an H-bearing member of the melilite group. The structure has two distinct layers. The one crystallographically distinct Ca site with eight-fold coordination is a square antiprism polyhedron. The Ca polyhedra are in a layer with the H atoms. A second layer consists of corner-sharing Si/Be atoms in tetrahedral coordination with O. One H atom is bonded to an apical O atom that is not shared by two tetrahedra. This H atom is present only when there is a Ca -site vacancy. The other H atom is loosely bonded to the same O atom but at a different site. The IR spectrum supports this H-bonding scheme. Additional hydroxylgugiaite data is given for the other localities.

Description: Rowleyite, $$[\mathrm{Na}{({\mathrm{NH}}_{4},\mathrm{K})}_{9}{\mathrm{Cl}}_{4}]{[{\mathrm{V}}_{2}^{5+,4+}(\mathrm{P},\mathrm{As}){\mathrm{O}}_{8}]}_{6}\cdot n[{\mathrm{H}}_{2}\mathrm{O},\mathrm{Na},{\mathrm{NH}}_{4},\mathrm{K},\mathrm{Cl}]$$ , is a new mineral species from the Rowley mine, Maricopa County, Arizona, U.S.A. It was found in an unusual low-temperature, apparently post-mining suite of phases that include various vanadates, phosphates, oxalates, and chlorides, some containing $${\mathrm{NH}}_{4}^{+}$$ . Other secondary minerals found in association with rowleyite are antipinite, fluorite, mimetite, mottramite, quartz, salammoniac, struvite, vanadinite, willemite, wulfenite, and several other potentially new minerals. Analyzed 13 C values for the antipinite in association with rowleyite are consistent with a bat guano source. Crystals of rowleyite are very dark brownish green (appearing black) truncated octahedra up to about 50 μm in diameter. The streak is brownish green, the luster is vitreous, very thin fragments are transparent. The Mohs hardness is about 2, the tenacity is brittle, fracture is irregular, there is no cleavage, and the measured density is 2.23(2) g/cm 3 . Rowleyite is optically isotropic with n = 1.715(5). Electron microprobe analyses yielded the empirical formula $${[{({\mathrm{NH}}_{4})}_{8.81}{\mathrm{Na}}_{3.54}{\mathrm{K}}_{2.58})}_{\Sigma 14.93}{\mathrm{Cl}}_{6.29}{({\mathrm{H}}_{2}\mathrm{O})}_{16}][{({\mathrm{V}}_{9.36}^{5+}{\mathrm{V}}_{2.64}^{4+})}_{\Sigma 12}{({\mathrm{P}}_{5.28}{\mathrm{As}}_{0.72}^{5+})}_{\Sigma 6}{\mathrm{O}}_{48}]$$ . Raman and infrared spectroscopy confirmed the presence of NH 4 and H 2 O. Rowleyite is cubic, $$Fd\overline{3}m$$ , with a = 31.704(14) Å, V = 31867(42) Å 3 , and Z = 16. The crystal structure of rowleyite ( R 1 = 0.040 for 1218 F o 〉 4 F reflections) contains [V 4 O 16 ] 12+ polyoxovanadate units that link to one another via shared vertices with [(P,As)O 4 ] 3– tetrahedra to form a 3D framework possessing large interconnected channels. The channels contain a 3D ordered [Na(NH 4 ,K) 9 Cl 4 ] 6+ salt net, which apparently served as a template for the formation of the framework. In that respect, rowleyite can be considered a salt-inclusion solid (SIS). The rowleyite framework is among the most porous known.

Description: The crystal structure of the mineral kurilite, a rare silver chalcogenide, was solved using intensity data collected from a twinned crystal of type material from the Prasolovskoe deposit, Kunashir Island, Kuril islands (Russia). The study revealed that the structure is trigonal, space group R 3{macron} , with cell parameters: a 15.8135(18), c 19.618(3) Å, and V 4248.6(9) Å 3 . The refinement had a final R index of 0.0218 for 2513 observed reflections [ I 〉 2( I )] and 0.0265 for all 2776 independent reflections and 193 parameters. Three Te sites, three Se sites, and ten Ag sites occur in the crystal structure of kurilite. The silver cations form various crystal-chemical environments, as is typical of many intermetallic compounds. The Ag positions correspond to the most pronounced probability density function ( pdf ) locations (modes) of diffusion-like paths. The d 10 silver ion distribution was determined by means of a Gram-Charlier development of the atomic displacement factors. Crystal-chemical features are discussed in relation to other copper and silver tellurides and pure metals. The disorder observed for the Ag atoms is compared to that of other natural fast ionic conductors, such as the pearceite-polybasite group minerals. On the basis of information gained from the structural characterization, the Z of the crystal-chemical formula was revised to 18 instead of 15, as previously reported.

Description: The crystal structure of schneiderhöhnite, Fe 2+ Fe 3+ 3 As 3+ 5 O 13 , triclinic P , a 8.945(3), b 10.022(3), c 9.161(4) Å, α 62.942(5), β 116.072(6), 81.722(6)°, has been refined to an R 1 value of 1.4%. The structure is very close to that reported by Hawthorne (1985) , but detailed examination of the structural connectivity shows that schneiderhöhnite is better described as a sheet structure than as a framework structure. Zig-zag chains of edge-sharing Fe (1), Fe (2), Fe (3) (= Fe 3+ ) octahedra extend parallel to the c axis, and these chains are cross-linked into a corrugated sheet by tetramers of edge-sharing Fe (4) (= Fe 3+ ) and Fe (5) (= Fe 2+ ) octahedra. (As 3+ O 3 ) triangular pyramids decorate the surface of this sheet of octahedra as single (AsO 3 ) groups, with all three short bonds linked to anion vertices of the octahedra, and as two crystallographically distinct [As 2 O 5 ] dimers with four short bonds (two from each As 3+ ) to octahedron vertices. The sheets are connected along [100] via the bridging anion of one of the two [As 2 O 5 ] dimers that bonds to an Fe 2+ octahedron of the adjacent sheet, imparting a strong sheet-like character to the structure and accounting for the perfect (100) cleavage.

Description: Wiklundite, ideally Pb 2 [4] (Mn 2+ ,Zn) 3 (Fe 3+ ,Mn 2+ ) 2 (Mn 2+ ,Mg) 19 (As 3+ O 3 ) 2 [(Si,As 5+ )O 4 ] 6 (OH) 18 Cl 6 , is a new arseno-silicate mineral from Långban, Filipstad, Värmland, Sweden. Both the mineral and the name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2015-057). Wiklundite and a disordered wiklundite-like mineral form radiating, sheaf-like aggregates (up to 1 mm long) of thin brownish-red and slightly bent lath-shaped crystals. It occurs in a dolomite-rich skarn in association with tephroite, mimetite, turneaurite, johnbaumite, jacobsite, barite, native lead, filipstadite and parwelite. Wiklundite is reddish brown to dark brown, and the streak is pale yellowish brown. The lustre is resinous to sub-metallic, almost somewhat bronzy, and wiklundite does not fluoresce under ultraviolet light. The calculated density is 4.072 g cm –3 . Wiklundite is brittle with an irregular fracture, and has perfect cleavage on {001}; no parting or twinning was observed. Wiklundite is uniaxial (–), orange red and non-pleochroic in transmitted light, but shows incomplete extinction and distorted interference figures, preventing complete determination of optical properties. Electron-microprobe analysis (H 2 O calculated from the structure) of wiklundite gave SiO 2 11.17, Al 2 O 3 0.06, Fe 2 O 3 4.46, As 2 O 5 0.75, As 2 O 3 6.81, MnO 47.89, ZnO 0.78, CaO 0.09, PbO 14.48, Cl 6.65, H 2 O 5.18, O=Cl 2 –1.50, total 97.11 wt.%, As valences and H 2 O content taken from the crystal-structure refinement, and Fe 3+ /(Fe 2+ + Fe 3+ ) determined by Mössbauer spectroscopy. Wiklundite is hexagonal-rhombohedral, space group R 3 c, a = 8.257(2), c = 126.59(4) Å, V = 7474(6) Å 3 , Z = 6. The crystal structure of wiklundite was solved by direct methods and refined to a final R 1 index of 3.2%. The structure consists of a stacking of five layers of polyhedra: three layers consist of trimers of edge-sharing Mn 2+ -dominant octahedra linked by (SiO 4 ) tetrahedra, (Fe 3+ (OH) 6 ) dominant octahedra and (AsO 3 ) triangular pyramids; one layer of corner-sharing (SiO 4 ) and (Mn 2+ O 4 ) tetrahedra; and one layer of (Mn 2+ Cl 6 ) octahedra and (Pb 2+ (OH) 3 Cl 6 ) polyhedra. The mineral is named after Markus Wiklund ( b . 1969) and Stefan Wiklund ( b . 1972), the well-known Swedish mineral collectors who jointly found the specimen containing the mineral.

Description: Telluromandarinoite, a tellurite, is a new mineral species from the Wendy open pit, Tambo mine, El Indio-Tambo mining property, Coquimbo Province, Chile. The ideal endmember telluromandarinoite formula is Fe 3+ 2 Te 4+ 3 O 9 ·6H 2 O and it is the Te 4+ analogue of the selenite mineral mandarinoite, Fe 3+ 2 Se 4+ 3 O 9 ·6H 2 O. These deposits are located in rhyolitic and dacitic pyroclastic volcanic rocks of Tertiary age (8–11 Ma) that are strongly hydrothermally altered. The mineralization in the Tambo area is characterized by high-level epithermal veins and breccias located along roughly east–west structures. Hydrothermal breccias consisting of silicified clasts of dacite tuffs cemented by a silica/barite/alunite matrix are common at the occurrence. In fact, all studied specimens containing tellurite mineralization are associated with alunite. Telluromandarinoite is translucent, pale green, with a white streak and vitreous luster. It forms as individual platy crystals, 0.2 mm or less in size, but more commonly as aggregates of platy crystals. The crystals are too small to allow a Mohs hardness determination; they are brittle with an uneven fracture and no observed cleavage or parting. Telluromandarinoite is biaxial positive with α = 1.750(3), β = 1.807(3), and = 1.910(5), with a calculated 2 V = 76.9°. The optical orientation is Y = b , c {circumflex} Z = 10° in obtuse β. No dispersion was noted and no pleochroism was observed. An average of 10 electron microprobe analyses gave SeO 2 22.91, TeO 2 44.30, Fe 2 O 3 26.43, and H 2 O (calc.) 17.59, total 111.23 wt.%. The mineral loses H 2 O in vacuum, so the high totals obtained were expected. The empirical formula (based on 15 O atoms) is Fe 3+ 2.03 (Te 4+ 1.71 Se 4+ 1.27 ) 2.98 O 9 ·6H 2 O with Z = 4, and D calc = 3.372 g/cm 3 . Spot analyses gave stoichiometries that range from telluromandarinoite Fe 3+ 2.03 (Te 4+ 2.12 Se 4+ 0.86 ) 2.98 O 9 ·6H 2 O to mandarinoite Fe 3+ 2.07 (Se 4+ 1.64 Te 4+ 1.31 ) 2.95 O 9 ·6H 2 O. A crystal-structure analysis shows the mineral to be monoclinic, space group P 2 1 / c , with a 16.9356(5), b 7.8955(3), c 10.1675(3) Å, β 98.0064(4)°, and V 1346.32(13) Å 3 . The strongest lines in the X-ray powder pattern [ d in Å,( I ),( hkl )] are: 8.431(44)(200), 7.153(100) , 3.5753(41) , 3.4631(21) , 2.9964(34) , 2.8261(19)(412). The crystal structure of telluromandarinoite is similar to that of emmonsite, Fe 3+ 2 Te 4+ 3 O 9 ·2H 2 O.

Description: Wernerbaurite (IMA 2012–064) and schindlerite (IMA 2012–063) from the St. Jude mine, Slick Rock district, San Miguel County, Colorado, USA, were described as hydronium-bearing decavanadate minerals with the formulae {[Ca(H 2 O) 7 ] 2 (H 2 O) 2 (H 3 O) 2 }{V 10 O 28 } and {[Na 2 (H 2 O) 10 ](H 3 O) 4 }{V 10 O 28 }, respectively. Because these phases correspond to known synthetic phases with these formulae, the presence of NH 4 in these minerals was not considered. Recent investigations of a similar phase discovered at a vanadium locality in the Fergana Valley of Kyrgyzstan showed it to contain NH 4 , leading us to reanalyze the original electron-microprobe mounts of wernerbaurite and schindlerite, specifically seeking N; those analyses confirmed the presence of sufficient NH 4 to replace the originally assigned H 3 O. With the additional H sites included and O replaced by N at the NH 4 sites, the structure refinement residual improved for wernerbaurite from R 1 = 3.41% to R 1 = 3.26% and for schindlerite from R 1 = 3.99% to R 1 = 3.70%. The newly assigned NH 4 sites exhibited normal NH 4 –O bond distances and coordination and reasonable bond-valence sums. The H 3 O synthetic equivalents of both phases had been reported, as well as the NH 4 synthetic equivalent of schindlerite. Subsequent to the publication of the original description of the minerals, the NH 4 equivalent of wernerbaurite has also been reported.

Description: The crystal structure of gianellaite, [(NHg 2 ) 2 ](SO 4 )(H 2 O) x , cubic, F 3 m , a = 9.521(6) Å V = 863.1(1.6) Å 3 , Z = 4, was solved by direct methods and refined to an R 1 index of 2.1% based on 167 unique observed reflections collected on a three-circle rotating-anode (Mo K α X-radiation) diffractometer equipped with multilayer optics and an APEX-II detector. In the structure of gianellaite, nitrogen-centred (NHg 4 ) 5+ tetrahedra share all corners to form a framework of tetrahedra with an ordered arrangement of interstitial (SO 4 ) 2– tetrahedra that show strong orientational disorder. Infrared spectroscopy in the principal O–H stretching region shows peaks at ~3300 and 1600 cm –1 , indicating the presence of (H 2 O), the position(s) of which could not be discerned in difference-Fourier maps.