ALBERT

Description: Tapiaite (IMA2014-024), Ca 5 Al 2 (AsO 4 ) 4 (OH) 4 ·12H 2 O, is a new mineral from the Jote mine, Tierra Amarilla, Copiapó Province, Atacama, Chile. The mineral is a late-stage, low-temperature, secondary mineral occurring with conichalcite, joteite, mansfieldite, pharmacoalumite, pharmacosiderite and scorodite in narrow seams and vughs in the oxidized upper portion of a hydrothermal sulfide vein hosted by volcanoclastic rocks. Crystals occur as colourless blades, flattened on {101I} and elongated and striated along [010], up to ~0.5 mm long, and exhibiting the forms {101I}, {101} and {111}. The blades are commonly intergrown in subparallel bundles and less commonly in sprays. The mineral is transparent and has a white streak and vitreous lustre. The Mohs hardness is estimated to be between 2 and 3, the tenacity is brittle, and the fracture is splintery. It has two perfect cleavages on {101} and {101I}. The calculated density based on the empirical formula is 2.681 g cm –3 . It is optically biaxial (+) with α = 1.579(1), β = 1.588(1), = 1.610(1) (white light), 2V meas = 66(2)° and 2V calc = 66°. The mineral exhibits no dispersion. The optical orientation is X [101I]; Y = b, Z [101]. The electron-microprobe analyses (average of five) provided: Na 2 O 0.09, CaO 24.96, CuO 0.73, Al 2 O 3 10.08, Fe 2 O 3 0.19, As 2 O 5 40.98, Sb 2 O 5 0.09, H 2 O 23.46 (structure), total 100.58 wt.%. In terms of the structure, the empirical formula (based on 32 O a.p.f.u.) is (Ca 4.83 $${\mathrm{Cu}}_{0.10}^{2+}$$ Na 0.03 ) 4.96 (Al 2.14 $${\mathrm{Fe}}_{0.03}^{3+}$$ ) 2.17 [( $${\mathrm{As}}_{3.87}^{5+}$$ $${\mathrm{Sb}}_{0.01}^{5+}$$ ) 3.88 O 16 ][(OH) 3.76 (H 2 O) 0.24 ] 4 (H 2 O) 10 ·2H 2 O. The mineral is easily soluble in RT dilute HCl. Tapiaite is monoclinic, P 2 1 / n , with unit-cell parameters a = 16.016(1), b = 5.7781(3), c = 16.341(1) Å, β = 116.704(8)°, V = 1350.9(2) Å 3 and Z = 2. The eight strongest lines in the powder X-ray diffraction pattern are [ d obs Å ( I )( hkl )]: 13.91(100)(1I01), 7.23(17)(200,002), 5.39(22)(110,011), 4.64(33)(1I12,2I11,3I03), 3.952(42)(1I13,3I11,2I13), 3.290(35)(2I14,4I12,1I14,4I11), 2.823(39)(303,3I15) and 2.753(15)(5I13,1I15,121,5I11). The structure of tapiaite ( R 1 = 5.37% for 1733 F o 〉 4 F ) contains Al(AsO 4 )(OH) 2 chains of octahedra and tetrahedra that are topologically identical to the chain in the structure of linarite. CaO 8 polyhedra condense to the chains, forming columns, which are decorated with additional peripheral AsO 4 tetrahedra. The CaO 8 polyhedra in adjacent columns link to one another by corner-sharing to form thick layers parallel to {101I} and the peripheral AsO 4 tetrahedra link to CaO 6 octahedra in the interlayer region, resulting in a framework structure.

Description: Bariopharmacoalumite, ideally Ba0.5Al4(AsO4)3(OH)4{middle dot}4H2O, is a new mineral from Cap Garonne, France. It occurs in several places within the mine as colourless to pale yellow interpenetrating cubes up to 0.5 mm across. Bariopharmacoalumite is transparent to translucent, with a white streak, has an adamantine lustre and imperfect cleavage on {001}. The Vickers hardness is 234.35 and the Mohs harness is 3.5. Bariopharmacoalumite is isotropic, with n = 1.573 (upper estimate) [calculated from reflectance values at 589 nm using Fresnel Equations]. The empirical formula, based on 20 oxygen atoms, is: (Ba0.54Cu0.03K0.01){Sigma}0.58(Al3.99Fe0.02){Sigma}4.01(AsO4)3.00(OH)3.85O0.15{middle dot}4H2O and the calculated density (on the basis of the empirical formula and single-crystal unit cell) is 2.580 g/cm3. The four strongest lines in the X-ray powder diffraction pattern are [dobs(A), Iobs,(hkl)]: 7.759, 100, (001); 5.485, 27, (011); 3.878, 27, (002); 4.454, 18, (011). Bariopharmacoalumite from Cap Garonne is cubic, space group P[IMG]f1.gif" ALT="Formula" BORDER="0"〉3m with a = 7.742(4) A, V = 464.2(4) A3 and Z = 1. The crystal structure was solved by direct methods and refined to R1 = 0.0705 for 215 reflections with I 〉 4{sigma}(I) and is consistent with members of the pharmacosiderite supergroup. Data are also presented from zoned bariopharmacoalumite-bariopharmacosiderite crystals found at the Mina Grande mine, Chile.

Description: The new mineral canutite (IMA2013-070), NaMn 3 [AsO 4 ][AsO 3 (OH)] 2 , was found at two different locations at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, halite, lavendulan, magnesiokoritnigite, pyrite, quartz and scorodite. Canutite is reddish brown in colour. It forms as prisms elongated on [201I] and exhibiting the forms {010}, {100}, {102}, {201} and {102I}, or as tablets flattened on {102} and exhibiting the forms {102} and {110}. Crystals are transparent with a vitreous lustre. The mineral has a pale tan streak, Mohs hardness of 21/2, brittle tenacity, splintery fracture and two perfect cleavages, on {010} and {101}. The calculated density is 4.112 g cm –3 . Optically, canutite is biaxial (+) with α = 1.712(3), β = 1.725(3) and = 1.756(3) (measured in white light). The measured 2V is 65.6(4)°, the dispersion is r 〈 v (slight), the optical orientation is Z = b ; X ^ a = 18° in obtuse β and pleochroism is imperceptible. The mineral is slowly soluble in cold, dilute HCl. The empirical formula (for tabular crystals from near the mine shaft), determined from electron-microprobe analyses, is (Na 1.05 Mn 2.64 Mg 0.34 Cu 0.14 Co 0.03 ) 4.20 As 3 O 12 H 1.62 . Canutite is monoclinic, C 2/ c , a = 12.3282(4), b = 12.6039(5), c = 6.8814(5) Å, β = 113.480(8)°, V = 980.72(10) Å 3 and Z = 4. The eight strongest X-ray powder diffraction lines are [ d obs Å( I )( hkl )]: 6.33(34)(020), 4.12(26)(2I21), 3.608(29)(310,1I31), 3.296(57)(1I12), 3.150(28)(002,131), 2.819(42)(400,041,330), 2.740(100)(240,4I02,112) and 1.5364(31)(multiple). The structure, refined to R 1 = 2.33% for 1089 F o 〉 4 F reflections, shows canutite to be isostructural with protonated members of the alluaudite group.

Description: Type specimens of the molybdoarsenates betpakdalite, natrobetpakdalite and obradovicite and the molybdophosphates mendozavilite, paramendozavilite and melkovite, and similar material from other sources, have been examined in an effort to elucidate the relations among these phases, which we designate as the heteropolymolybdate family of minerals. Using electron microprobe analysis, X-ray powder diffraction and single-crystal X-ray diffraction with crystal structure determination where possible, it was found that natrobetpakdalite, mendozavilite and melkovite are isostructural with betpakdalite and that obradovicite has a closely related structure.The betpakdalite and obradovicite structure types are based on frameworks containing four-member clusters of edge-sharing MoO6 octahedra that link by sharing corners with other clusters, with Fe3+O6 octahedra and with PO4 or AsO4 tetrahedra (T). The structures differ in the linkages through the Fe3+O6 octahedra, which produce different but closely related framework configurations. The structures contain two types of non-framework cation sites, which are designated A and B. In general, there are two or more A sites partially occupied by disordered, generally larger cations that are coordinated to O atoms in the framework and to H2O molecules. The B site is occupied by a smaller cation that is octahedrally coordinated to H2O molecules. The general formula for minerals with either the betpakdalite or the obradovicite structure is: [A2(H2O)nB(H2O)6][Mo8T2 O30+7(OH)7–x], where x is the total charge of the cations in the A and B sites (+3 to +7) and n is variable, ideally 17 for arsenates and 15 for phosphates. The ideal total number of A cations is defined as 2 in the general formula, but varies from 1 to 3.8 in analysed samples. Dominant cations at the A site include K, Na and Ca and at the B site Na, Ca, Mg, Cu and Fe. The combinations that have been identified in this study define six new heteropolymolybdate species.A suffix-based nomenclature scheme is established for minerals of the betpakdalite, mendozavilite and obradovicite groups, with the following root names based on the structure types and the T-site cations: betpakdalite (T = As), mendozavilite (T = P) and obradovicite (T = As). Two suffixes of the form -AB, corresponding to the dominant cations in the two different types of non-framework cation sites complete the species name. The historical name melkovite is retained rather than introducing mendozavilite-CaCa.Our investigation of the paramendozavilite type specimen revealed no paramendozavilite, but an apparently closely related new mineral; however, another sample of paramendozavilite analysed had K 〉 Na.

Description: Camaronesite (IMA 2012-094), [Fe 3+ (H 2 O) 2 (PO 3 OH)] 2 (SO 4 )·1–2H 2 O, is a new mineral from near the village of Cuya in the Camarones Valley, Arica Province, Chile. The mineral is a low-temperature, secondary mineral occurring in a sulfate assemblage with anhydrite, botryogen, chalcanthite, copiapite, halotrichite, hexahydrite, hydroniumjarosite, pyrite, römerite, rozenite and szomolnokite. Lavender-coloured crystals up to several mm across form dense intergrowths. More rarely crystals occur as drusy aggregates of tablets up to 0.5 mm in diameter and 0.02 mm thick. Tablets are flattened on {001} and exhibit the forms {001}, {104}, {015} and {018}. The mineral is transparent with white streak and vitreous lustre. The Mohs hardness is 21/2, the tenacity is brittle and the fracture is irregular, conchoidal and stepped. Camaronesite has one perfect cleavage on {001}. The measured and calculated densities are 2.43(1) and 2.383 g/cm 3 , respectively. The mineral is optically uniaxial (+) with = 1.612(1) and = 1.621(1) (white light). The pleochroism is O (pale lavender) 〉 E (colourless). Electron-microprobe analyses provided Fe 2 O 3 31.84, P 2 O 5 29.22, SO 3 15.74, H 2 O 23.94 (based on O analyses), total 100.74 wt.%. The empirical formula (based on 2 P a.p.f.u.) is: Fe 1.94 (PO 3 OH) 2 (S 0.96 O 4 )(H 2 O) 4 ·1.46H 2 O. The mineral is slowly soluble in concentrated HCl and extremely slowly soluble in concentrated H 2 SO 4 . Camaronesite is trigonal, R 32, with cell parameters: a = 9.0833(5), c = 42.944(3) Å, V = 3068.5(3) Å 3 and Z = 9. The eight strongest lines in the X-ray powder diffraction pattern are [ d obs Å( I )( hkl )]: 7.74(45)(101), 7.415(100)(012), 4.545(72)(110), 4.426(26)(018), 3.862(32)(021,202,116), 3.298(93)(027,119), 3.179(25)(208) and 2.818(25)(1·1·12,125). In the structure of camaronesite ( R 1 = 2.28% for 1138 F o 〉 4 F ), three types of Fe octahedra are linked by corner sharing with (PO 3 OH) tetrahedra to form polyhedral layers perpendicular to c with composition [Fe 3+ (H 2 O) 2 (PO 3 OH)]. Two such layers are joined through SO 4 tetrahedra (in two half-occupied orientations) to form thick slabs of composition [Fe 3+ (H 2 O) 2 (PO 3 OH)] 2 (SO 4 ). Between the slabs are partially occupied H 2 O groups. The only linkages between the slabs are hydrogen bonds. The most distinctive component in the structure consists of two Fe octahedra linked to one another by three PO 4 tetrahedra yielding an [Fe 2 (PO 4 ) 3 ] unit. This unit is also the key component in the sodium super-ionic conductor (NASICON) structure and has been referred to as the lantern unit. The polyhedral layers in the structure of camaronesite are similar to those in the structure of taranakite. The Raman spectrum exhibits peaks consistent with sulfate, phosphate, water and OH groups.

Description: The new mineral currierite (IMA2016-030), Na 4 Ca 3 MgAl 4 (AsO 3 OH) 12 ·9H 2 O, was found at the Torrecillas mine, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, canutite, chudobaite, halite, lavendulan, magnesiokoritnigite, quartz, scorodite and torrecillasite. Currierite occurs as hexagonal prisms, needles and hair-like fibres up to ~200 μm long, in sprays. The crystal forms are {100} and {001}. Crystals are transparent, with vitreous to silky lustre and white streak. The Mohs hardness is ~2, tenacity is brittle, but elastic in very thin fibres, and the fracture is irregular. Crystals exhibit at least one good cleavage parallel [001]. The measured density is 3.08(2) g cm –3 and the calculated density is 3.005 g cm –3 . Optically, currierite is uniaxial (–) with = 1.614(1) and = 1.613(1) (measured in white light). The mineral is slowly soluble in dilute HCl at room temperature. The empirical formula, determined from electron-microprobe analyses, is (Na 3.95 Al 2.96 Ca 2.74 Mg 1.28 Cu 0.13 K 0.08 Co 0.03 ) 11.80 ( ) 12 (O 56.96 Cl 0.04 ) 57 H 30.81. Currierite is hexagonal, P 622, with a = 12.2057(9), c = 9.2052(7) Å, V = 1187.7(2) Å 3 and Z = 1. The eight strongest powder X-ray diffraction lines are [ d obs Å( I )( hkl )]: 10.63(100)(100), 6.12(20)(110), 5.30(15)(200), 4.61(24)(002), 4.002(35)(210), 3.474(29)(202), 3.021(96)(212) and 1.5227(29)(440,334,612). The structure of currierite ( R 1 = 2.27% for 658 F o 〉 4 F reflections) is based upon a heteropolyhedral chain along c in which AlO 6 octahedra are triple-linked by sharing corners with AsO 3 OH tetrahedra. Chains are linked to one another by bonds to 8(4 + 4)-coordinated Na and 8-coordinated Ca forming a three-dimensional framework with large cavities that contain rotationally disordered Mg(H 2 O) 6 octahedra. The chain in the structure of currierite is identical to that in kaatialaite and a geometrical isomer of that in ferrinatrite. The mineral is named in honour of Mr. Rock Henry Currier (1940–2015), American mineral dealer, collector, author and lecturer.

Description: The new mineral juansilvaite (IMA2015-080), Na 5 Al 3 [AsO 3 (OH)] 4 [AsO 2 (OH) 2 ] 2 (SO 4 ) 2 ·4H 2 O, was found at the Torrecillas mine, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, canutite, halite, sulfur and a mahnertite-like phase. Juansilvaite occurs as bright pink blades up to ~0.5 mm long grouped in tightly intergrown radial aggregates and also as opaque dull pale pink rounded aggregates. Blades are flattened on {001}, elongated on [100] and exhibit the forms {001}, {111} and {20 1 }. Crystals are transparent, with vitreous lustre and white streak. The Mohs hardness is ~ 21/2, tenacity is brittle and fracture is irregular. Cleavage is very good on {001}. The measured density is 3.01(2) g cm –3 and the calculated density is 3.005 g cm –3 . Optically, juansilvaite is biaxial (+) with α = 1.575(1), β = 1.597(1), = 1.623(1) and 2V = 86(1)° (measured in white light). Dispersion is r 〈 v , slight, and the orientation is X = b ; Z ^ c = 27° in the obtuse angle β. The pleochroism is X 〉 Y Z in shades of pale pink. The mineral is slowly soluble in dilute HCl at room temperature. The empirical formula, determined from electron-microprobe analyses, is Na 4.95 Al 2.28 Cu 0.04 As 5.92 S 1.83 O 36 H 17.37 . Juansilvaite is monoclinic, C 2/ c , a = 18.1775(13), b = 8.6285(5), c = 18.5138(13) Å, β = 90.389(6)°, V = 2903.7(3) Å 3 and Z = 4. The eight strongest powder X-ray diffraction lines are [ d obs  Å( I )( hkl )]: 9.25(100)(002), 7.20(34)( 1 11), 4.545(34)(400), 3.988(39)( 14), 3.363(42)(314), 3.145(66)( 12,420), 2.960(68)( 22,422) and 2,804(33)(131, 4 23). The structure of juansilvaite ( R 1 = 3.82% for 2040 F o 〉 4 F reflections) contains layers made up of alternating corner-linked Al–O octahedra and acid-arsenate tetrahedra. Sodium cations occur both peripheral to the layers and within cavities in the layers. An SO 4 tetrahedron and an H 2 O group also are in the interlayer region.

Description: Tondiite, with the simplified formula Cu 3 Mg(OH) 6 Cl 2 , occurs as a rare supergene mineral in a phonolitic tephrite from the type locality, Vesuvius volcano, Italy, as well as associated with haydeeite in the Santo Domingo Mine, Arica Province, Chile. It is emerald green to bright green in colour and occurs in irregularly shaped crystals, often with stepped faces. Its calculated density is 3.503 g cm –3 . Tondiite crystallizes with the herbertsmithite structure type, space group R 3I m . Lattice parameters are a = 6.8377(7) Å and c = 14.088(2) Å for the holotype material. The c parameter may vary with Mg/Cu ratio and the presence of impurity atoms. The five strongest lines in the calculated powder diffraction pattern are [ d in Å( I )( hkil )]: 5.459(88)(101I1), 3.419(22)(112I0), 2.764(100)(112I3), 2.266(54)(022I4), 1.706(26)(224I0). Several tondiite crystals have been examined by single-crystal X-ray diffraction and by electron microprobe analysis. The observed Mg content ranges between 0.6 and 0.7 atoms per formula unit. The structural role of Mg is discussed.

Description: The new mineral torrecillasite (IMA2013-112), $$\mathrm{Na}{(\mathrm{As},\mathrm{Sb})}_{4}^{3+}$$ , was found at the Torrecillas mine, Iquique Province, Chile, where it occurs as a secondary alteration phase in association with anhydrite, cinnabar, gypsum, halite, lavendulan, magnesiokoritnigite, marcasite, quartz, pyrite, scorodite, wendwilsonite and other potentially new As-bearing minerals. Torrecillasite occurs as thin colourless prisms up to 0.4 mm long in jack-straw aggregates, as very thin fibres in puff balls and as massive intergrowths of needles. Prisms are elongated on [100] with diamond-shaped cross-section and irregular terminations. Crystals are transparent, with adamantine lustre and white streak. The Mohs hardness is 21/2, tenacity is brittle and fracture is irregular. Cleavage on (001) is likely. The calculated density is 4.056 g cm –3 . Optically, torrecillasite is biaxial (–) with α = 1.800(5), β = 1.96(1), = 2.03(calc.) (measured in white light). The measured 2V is 62.1(5)°, no dispersion or pleochroism were observed, the optical orientation is X = c , Y = b , Z = a . The mineral is very slowly soluble in H 2 O, slowly soluble in dilute HCl and rapidly soluble in concentrated HCl. The empirical formula, determined from electron-microprobe analyses, is (Na 1.03 Mg 0.02 ) 1.05 (As 3.39 Sb 0.62 ) 4.01 O 6.07 Cl 0.93 . Torrecillasite is orthorhombic, Pmcn , a = 5.2580(9), b = 8.0620(13), c = 18.654(3) Å, V = 790.7(2) Å 3 and Z = 4. The eight strongest X-ray powder diffraction lines are [ d obs Å( I )( hkl )]: 4.298(33)(111), 4.031(78)(014,020), 3.035(100)(024,122), 2.853(39)(115,123), 2.642(84)(124,200), 2.426(34)(125), 1.8963(32)(225) and 1.8026(29)(0·1·10,233). The structure, refined to R 1 = 4.06% for 814 F o 〉4 F reflections, contains a neutral, wavy As 2 O 3 layer parallel to (001) consisting of As 3+ O 3 pyramids that share O atoms to form six-membered rings. Successive layers are flipped relative to one another and successive interlayer regions contain alternately either Na or Cl atoms. Torrecillasite is isostructural with synthetic orthorhombic NaAs 4 O 6 Br.

Description: The natural hydroniumjarosite sample from Cerros Pintados (Chile) was investigated by electron microprobe, single-crystal X-ray diffraction and vibrational spectroscopy (Infrared and Raman). The chemical composition of studied specimens (wt.%, mean of seven analyses) obtained from electron microprobe (in wt.%): Na 2 O 1.30, K 2 O 0.23, CaO 0.04, Fe 2 O 3 50.49, Al 2 O 3 0.37, SiO 2 0.33, SO 3 33.88, H 2 O (calculated on the basis of (OH – +H 3 O + ) deduced from the charge balance) 13.32, total 99.98, corresponds to the empirical formula $${\left({\mathrm{H}}_{3}\mathrm{O}\right)}_{0.77}^{+}$$ (Na 0.20 K 0.02 ) 0.22 (Fe 2.95 Al 0.03 ) 2.98 (OH) 6.12 [(SO 4 ) 1.97 (SiO 4 ) 0.03 ] 2.00 (calculated on the basis of S + Si = 2 a.p.f.u. (atoms per formula unit)). The studied hydroniumjarosite is trigonal, with space group R 3I m , with a = 7.3408(2), c = 17.0451(6) Å and V = 795.46(4) Å 3 . The refined structure architecture is consistent with known jarosite-series minerals, including synthetic hydroniumjarosite. However, in the current study the presence of H 3 O + is well documented in difference Fourier maps, where characteristic positive difference Fourier maxima, with apparent trigonal symmetry, were localized in the vicinity of the O4 atom in the channel-voids of the structure. The structure of natural hydroniumjarosite, including the H atoms, was refined to R 1 = 0.0166 for 2113 unique observed reflections, with I obs 〉3( I ). The present structure model, which includes the position of the H atom within the hydronium ion, is discussed with regard to the vibration spectroscopy results and earlier published density-functional theory (DFT) calculations for the alunite-like structure containing H 3 O + .