ALBERT

Description: Chiappinoite-(Y) (IMA2014-040), ideally Y 2 Mn(Si 3 O 7 ) 4 , is a new mineral found in peralkaline syenitic ejecta from the Água de Pau volcano, Sãn Miguel Island, Azores District, Portugal. It was discovered by collector Luigi Chiappino of Milan, Italy, after whom the mineral is named. It occurs as colourless, thin to thick prisms, up to 1 mm long, with blunt chisel-like terminations, and exhibits the forms {100}, {010}, {001}, {110} and {011}. Crystals are transparent with vitreous lustre. The Mohs hardness is about 6 and the mineral is brittle with uneven fracture and one perfect cleavage on {001}. The measured and calculated densities are 3.09(2) and 3.073 g/cm 3 , respectively. Chiappinoite-(Y) is biaxial (–) and the refractive indices (white light) are α = 1.590(1), β = 1.5978(10), = 1.5982(10); 2 V meas = 24(1)° and 2 V calc = 25°. The mineral exhibits no dispersion and is nonpleochroic. The optical orientation is X = c , Y = b , Z = a . The empirical formula on 28 O apfu is (Y 1.17 Ce 0.18 Dy 0.10 Na 0.10 Nd 0.09 Er 0.08 La 0.07 Gd 0.07 Yb 0.06 Sm 0.03 Pr 0.02 ) 1.97 (Mn 2+ 0.61 Ca 0.25 Fe 2+ 0.09 ) 0.95 Si 12.07 O 28 . The eight strongest reflections in the X-ray diffraction pattern [ d obs. in Å ( I ) ( hkl )] are: 9.84 (90) (002), 4.129 (52) (024), 3.977 (48) (114), 3.544 (100) (211,042,202), 3.203 (48) (222), 2.999 (71) (044,204), 2.478 (67) (310,046,206) and 2.065 (57) (multiple). The mineral is orthorhombic, Ibam , with a = 7.5549(3), b = 15.2342(5), c = 19.6418(14) Å, V = 2260.6(2) Å 3 and Z = 4. The structure of chiappinoite-(Y) contains 3-tetrahedra-thick silicate layers consisting of sinuous batisite-like chains, above and below which are four-membered silicate rings. Eight-coordinate Y and Mn sites are located between the silicate layers. The structure is essentially identical to that of the synthetic phases PrNaSi 6 O 14 and NdNaSi 6 O 14 , except that the latter phases have an additional 12-coordinate Na site within the "cage" in the silicate layer.

Description: Zincalstibite-9R, a new polytype in the hydrotalcite supergroup is reported from the Monte Avanza mine, Italy. It occurs as pale blue curved disc-like tablets flattened on {001} intergrown to form rosettes typically less than 50 μm in diameter, with cyanophyllite and linarite in cavities in baryte. Zincalstibite-9R is uniaxial (−), with refractive indices ω = 1.647(2) and ε = 1.626(2) measured in white light. The empirical formula (based on 12 OH groups) is ( Al0.04)Σ2.00Al1.01 ( Si0.02)Σ0.99(OH)12, and the ideal formula is (Zn,Cu)2Al(OH)6[Sb(OH)6]. Zincalstibite-9R crystallizes in space group R3İ, with a = 5.340(2), c = 88.01(2) Å, V = 2173.70(15) Å3 and Z = 9. The crystal structure was refined to R1 = 0.0931 for 370 unique reflections [Fo 〉 4σ(F)] and R1 = 0.0944 for all 381 unique reflections. It has the longest periodic layer stacking sequence for a layered double hydroxide compound reported to date.

Description: Omsite (IMA 2012-025) is a new mineral from the Correc d'en Llinassos, Oms, Pyrénées-Orientales Department, France. It occurs as bright yellow to amber yellow discoidal tablets, flattened on {001}, which form rosettes typically 50–100 μm in diameter. Omsite generally crystallizes on siderite without associated supergene minerals; it occurs less commonly with glaukosphaerite. Crystals have a vitreous to resinous lustre, and are transparent to translucent. Omsite is not fluorescent in either short-wave or long-wave ultraviolet light. It has an estimated hardness of 3 on the Mohs' scale, is brittle with an irregular fracture, and has one poor cleavage on {001}. The calculated density is 3.378 g cm−3. Crystals are uniaxial (−), with indices of refraction of ω = 1.728(3) and ε = 1.66(1), measured in white light. Pleochroism is ω = orange-yellow, ε = pale orange-yellow; ω 〉 ε. The empirical formula [based on 12 (OH + Cl) p.f.u.] is ( Mg0.107 )Σ1.916 ( As0.072Na0.029)Σ1.048OH11.967Cl0.033. Omsite crystallizes in space group P3İ, with unit-cell parameters a = 5.3506(8), c = 19.5802(15) Å, V = 485.46(10) Å3 and Z = 2 determined by single crystal X-ray diffraction. The five strongest lines in the X-ray powder diffraction pattern [d in Å, (Irel), (hkl)] are as follows: 4.901, (100), (004); 4.575, (83), (011); 2.3539, (81), (114İ); 1.8079, (48), (118İ); 3.781, (34), (103). The crystal structure was solved to R1 = 0.0896 for 356 observed reflections [Fo〉4σFo] and 0.1018 for all the 469 unique reflections. Omsite is a layered double hydroxide (LDH) mineral, with a topology consistent with members of the hydrotalcite supergroup and cualstibite group.

Description: Wayneburnhamite (IMA2015-124), Pb 9 Ca 6 (Si 2 O 7 ) 3 (SiO 4 ) 3 , is a new mineral from the Commercial quarry, Crestmore, Riverside County, California, where it occurs as a metasomatic mineral on fracture surfaces in vesuvianite/wollastonite rock. Wayneburnhamite crystals are sky-blue hexagonal tablets and prisms up to 0.5 mm in maximum dimension. The streak is white. Crystals are transparent to translucent with vitreous to resinous luster. The Mohs hardness is 31/2, the tenacity is brittle, the fracture is conchoidal, and there is no cleavage. The calculated density is 5.271 g/cm 3 . The mineral is optically uniaxial (+), with w = 1.855(5), and e = 1.875(5) (white light). The pleochroism is E sky blue and O lighter sky blue; E 〉 O weak. Raman and infrared spectra are consistent with the crystal structure, but suggest a very minor hydrous component. The empirical formula (based on 9 Si apfu) is $${({\mathrm{Pb}}_{8.33}{\mathrm{Sr}}_{0.04}{\square }_{0.63})}_{\mathrm{\Sigma }9.00}{({\mathrm{Ca}}_{5.40}{\mathrm{Cu}}_{0.27}^{2+}{\square }_{0.33})}_{\mathrm{\Sigma }6.00}{\mathrm{Si}}_{9}{\mathrm{S}}_{0.21}{\mathrm{O}}_{32.64}{\mathrm{Cl}}_{0.05}$$ . Wayneburnhamite is hexagonal, $$P\overline{6}$$ , a = 9.8953(9), c = 10.2054(7) Å, V = 865.40(17) Å 3 , and Z = 1. The eight strongest lines in the X-ray powder diffraction pattern are [ d obs in Å( I )( hkl )]: 4.95(52)(110); 4.45(64)(111); 3.550(77)(112); 3.232(54)(120); 3.086(100)(121); 2.847(60)(300); 2.798(48)(113); and 2.734(83)(212). The structure determination ( R 1 = 3.01% for 1063 F o 〉 4 F ) shows wayneburnhamite to be an apatite polysome isostructural with ganomalite, differing only in that the site occupied dominantly by Mn in the structure of ganomalite is occupied dominantly by Ca in the structure of wayneburnhamite. The structure refinement of wayneburnhamite appears to represent a rare case in which the approximate locations of the Pb 2+ 6s 2 lone-electron pairs can be seen as electron density residuals.

Description: Dagenaisite, Zn 3 Te 6+ O 6 , is a new mineral from the Gold Chain mine, Tintic district, Juab County, Utah, U.S.A. It is a late-stage secondary phase formed by the oxidative alteration of earlier Te- and Zn-bearing minerals. It is associated with cinnabar, dugganite, eurekadumpite, and gold in vugs in a matrix composed of quartz and dolomite. The mineral occurs as tiny light greenish-gray platelets, generally intermixed with amorphous material, forming porous masses that are apparently replacements of earlier phases. The streak is white, the luster is pearly, and crystals are transparent to translucent. The hardness could not be measured, but appears to be 〈2 (Mohs). The tenacity is flexible, the fracture is irregular, and cleavage was not observed. The calculated density is 6.00 g/cm 3 for the empirical formula. At room temperature, the mineral is slowly soluble in dilute HCl and rapidly soluble in concentrated HCl. Optical properties could not be determined. Electron-microprobe analyses gave the empirical formula (Zn 2.39 Cu 0.36 Ca 0.06 Mn 0.03 As 0.03 Si 0.02 ) 2.89 Te 1.02 O 6 . The mineral is monoclinic, space group C 2/ c , with cell parameters a 14.87(2), b 8.88(2), c 10.37(2) Å, β 93.33(2)°, V 1367(4) Å 3 , and Z = 12. The five strongest lines in the X-ray powder diffraction patterns are [ d obs Å( I )( hkl )]: 4.311(30)(310), 3.029(44)(222), 2.744(68) , 2.539(100) , and 1.6568(48) . The mineral is the natural counterpart of synthetic Zn 3 Te 6+ O 6 , which has a structure based on an approximate close packing of O atoms in an hhchhc sequence along [100].

Description: Esquireite, BaSi 6 O 13 ·7H 2 O, is a new mineral from the Esquire #1 claim along Rush Creek, eastern Fresno County, California, USA, and a Ba-silicate lens on the NW slope of Trumbull Peak, Mariposa County, California, USA. Esquireite is a low-temperature hydrothermal alteration product of sanbornite and is found on surfaces of sanbornite. The mineral occurs as colorless rectangular blades, elongated and striated parallel to [010] and flattened on {001}. The streak is white, the luster is vitreous to pearly, and the crystals are transparent. The Mohs hardness is about 2. The tenacity is somewhat flexible, but not elastic, with brittle failure. The fracture is irregular and there are two cleavages: perfect on {001} and fair on {100}. The measured and calculated densities are 2.18(2) g/cm 3 and 2.237 g/cm 3 , respectively. Esquireite is biaxial (+), with α 1.477(1), β 1.481(1), 1.492 (calc.) (white light); 2 V meas = 63.8(6)°; no dispersion or pleochroism; optical orientation: Y = b ; Z ^ c 22° in obtuse β. Six electron-microprobe analyses gave the following empirical formula, based on 20 O apfu : Ba 0.95 Si 6.00 O 20 H 14.10 . Esquireite is monoclinic, space group C 2, with cell parameters a 13.601(4), b 4.9222(10), c 15.092(5) Å, β 111.578(19)°, V 939.6(4) Å 3 , and Z = 2. The eight strongest lines in the X-ray powder diffraction patterns are [ d obs Å( I )( hkl )]: 7.02(38)(002), 5.11(33)(201), 4.649(66)(003, 2{macron} 03), 4.191(100)(111), 3.339(65)( 4{macron} 02, 3{macron} 11, 3{macron} 12), 2.967(32)( 2{macron} 05, 1{macron} 14,311), 2.343(33)(multiple), and 2.261(35)(multiple). The crystal structure ( R 1 = 10.8% for 323 reflections with F o 〉 4 F ) contains four-tetrahedra-thick [Si 6 O 13 ] 2– silicate layers with Ba(H 2 O) 8 2+ polyhedra between the layers.