ALBERT

Description: A bstract The crystal structure of faheyite, ideally Mn 2+ Fe 3+ 2 [Be 2 (PO 4 ) 4 ](H 2 O) 6 , trigonal, a 9.404(7), c 15.920(11) Å, V 1219(2) Å 3 , Z = 3, space group P 3 1 21, has been solved and refined to an R 1 index of 4.4% with single-crystal X-ray diffraction data collected from a twinned fiber. There are two P sites that are tetrahedrally coordinated by O atoms with 〈 P –O〉 distances of 1.52 and 1.54 Å, respectively, one Be site tetrahedrally coordinated by O atoms with a 〈 Be –O〉 distance of 1.63 Å, one Mn site occupied by Mn 2+ coordinated by four O atoms and two (H 2 O) groups with a 〈 Mn –O〉 distance of 2.22 Å, and one Fe site occupied by Fe 3+ coordinated by four O atoms and two (H 2 O) groups with a 〈 Fe –O〉 distance of 2.01 Å. Each vertex of the Be tetrahedron is shared with a vertex of a neighboring P tetrahedron, and two vertices of each P tetrahedron are shared with neighboring Be tetrahedra to form a corner-sharing [Be(PO 4 ) 2 ] chain, with P tetrahedra flanking the Be tetrahedra of the central spine in the sequence - P (1)/ P (1)- Be - P (2)/ P (2)- Be -. Faheyite has a chiral structure, with the [Be(PO 4 ) 2 ] chain twisting about the c -axis in a clockwise direction for the refined P 3 1 21 enantiomer. The Mn octahedron lies along the 3 1 screw axis within the core region of the [Be(PO 4 ) 2 ] chain, forming [MnBe 2 (PO 4 ) 4 ] spires that are wrapped by Fe octahedra that share vertices with P tetrahedra. The crystal structures of fransoletite and parafransoletite also contain beryllophosphate chains topologically identical to that found in faheyite, although the [Be(PO 4 )(PO 3 OH)] chain in fransoletite and parafransoletite is straight, whereas the [Be(PO 4 ) 2 ] chain in faheyite forms a helix about the central c -axis.

Description: Fontarnauite was discovered in cores recovered from the Kütahya-Emet 2 and 188 (named here as Doğanlar) boreholes drilled in the Emet borate basin near the village of Doğanlar, Kütahya Province, Western Anatolia, Turkey. The Emet (or Emet-Hisarcık) basin is one of the Neogene basins in western Turkey bearing a borate-rich unit intercalated with Miocene sediments. Fontarnauite is most commonly associated with probertite, glauberite, and celestine and occurs as isolated colorless to light-brown prismatic crystals or as clusters of crystals less than 5 mm long. Fontarnauite is brittle, with a Mohs hardness of 21/2–3, and perfect {010} cleavage. D calc = 2.533 g/cm 3 . The new mineral is optically biaxial (–), α 1.517(2), β 1.539(2), 1.543(2) (590 nm); 2 V meas = 46(1)°; 2 V calc = 46°; X ^ a 95.0° (β obtuse); Y // b , Z ^ c 81.9° (β acute). Dispersion is r 〉 v , medium to weak. The chemical composition (electron microprobe; B and H from the crystal-structure refinement) is as follows: SO 3 17.75, B 2 O 3 38.66, CaO 2.26, SrO 18.98, Na 2 O 12.65, K 2 O 1.70, H 2 O 10.01, total 102.01 wt.%. The empirical formula (based on 15 O atoms per formula unit) is (Na 1.84 K 0.16 ) 2.00 (Sr 0.82 Ca 0.18 ) 1.00 S 1.00 B 5 H 5 O 15 ; the endmember formula is Na 2 Sr(SO 4 ) [B 5 O 8 (OH)](H 2 O) 2 based on the crystal-structure refinement. Single-crystal X-ray studies gave the space group P 2 1 /c, a 6.458(2), b 22.299(7), c 8.571(2) Å, β 103.047(13)°, V 1202.5(1.0) Å 3 , Z = 4. Structure refinement ( R 1 = 2.9%) revealed that two BO 4 tetrahedra and three BO 3 triangles share vertices to form B 5 O 10 (OH) units that link to other B 5 O 10 (OH) units along [100] and [001] to give a [B 5 O 8 (OH)] sheet parallel to (010). Within the central cavities of opposing sheets are the H 2 O groups, SO 4 tetrahedra, and Na (1) sites; the Sr and Na (2) sites occupy the interstices of a given sheet. The region of the structure where opposing cusps of neighboring sheets approach each other is dominated by weaker H-bonding associated with the OH and H 2 O groups, in accord with the observed perfect {010} cleavage. The strongest lines in the powder X-ray diffraction pattern, obtained after profile fitting using the Le Bail method, are as follows [ d in Å ( I ) ( hkl )]: 11.1498 (100)(020), 3.3948 (8)(061), 3.3389 (20)(042), 3.1993, 3.1990 (10)(160, 1 42), 3.0458(10)(052), 3.0250(7)(220), 2.7500 (10)( 2 22,142), 2.3999 (8)(260), 2.2300, 2.2284(7)(0 10 0,222), 1.9241, 1.9237(7)(311, 2 24). The holotype is deposited in the mineralogy collection of the Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada, accession number M56745.

Description: A bstract The crystal structure of mammothite, Pb 6 Cu 4 AlSbO 2 (SO 4 ) 2 Cl 4 (OH) 16 , is monoclinic in acentric space group C 2, with a 18.959(4), b 7.3398(19), c 11.363(3) Å, β 112.428(9){ring}, V 1461.6(1.0) Å 3 , and Z = 2. It has been refined to an R index of 0.019 on the basis of 3878 observed reflections. There are three crystallographically distinct Pb sites with two different co-ordinations: [Pb1O 8 Cl 1 ] is a mono-capped square antiprism polyhedron, while [Pb21O 7 Cl 2 ] and [Pb22O 7 Cl 2 ] are tri-capped trigonal prisms. Both Cu 2+ sites have distorted [4 + 2] octahedral coordination due to the Jahn-Teller effect. The Al and Sb sites are regular-octahedral co-ordination with oxygen atoms. The [SO 4 ] tetrahedron is quite distorted, with S–O bond lengths varying from 1.45 to 1.52 Å and subtended O–S–O angles varying from 106 to 113{ring}. In the structure there are eight (OH) – anions. All eight H atoms pfu were located, and it is these structure sites that reduce the symmetry from centric to acentric. Although mammothite is classified as a framework structure, it has a distinct layering. There are two layer types in the mammothite structure that parallel (001). There are three octahedrally coordinated sites; two are occupied by Cu atoms and one by an Al atom, in the octahedral layer. The tetragonal dipyramids [CuØ 6 ] are linked forming ‘olivine-like’ chains parallel to the b -axis. The second layer, termed the cross-linked layer, has three [PbØ 9 ] polyhedra with shared edges forming chains parallel to the b -axis, like the [CuØ 6 ] tetragonal dipyramids. These chains are cross-linked by edge-sharing [SbO 6 ] octahedra and decorated with [SO 4 ] groups. The H atoms are in ‘holes’ within both layers.

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: 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: 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.