José Moacyr Vianna Coutinho

Menezesite, the first natural heteropolyniobate, from Cajati, São Paulo, Brazil: Description and crystal structure

Abstract Menezesite, ideally Ba2MgZr4(BaNb12O42)·12H2O, occurs as a vug mineral in the contact zone between dolomite carbonatite and “jacupirangite” (=a pyroxenite) at the Jacupiranga mine, in Cajati county, São Paulo state, Brazil, associated with dolomite, calcite, magnetite, clinohumite, phlogopite, ancylite-(Ce), strontianite, pyrite, and tochilinite. This is also the type locality for quintinite-2H. The mineral forms rhombododecahedra up to 1 mm, isolated or in aggregates. Menezesite is transparent and displays a vitreous luster; it is reddish brown with a white streak. It is non-fluorescent. Mohs hardness is about 4. Calculated density derived from the empirical formula is 4.181 g/cm3. It is isotropic, nmeas > 1.93(1) (white light); ncalc = 2.034. Menezesite exhibits weak anomalous birefringence. The empirical formula is (Ba1.47K0.53Ca0.31Ce0.17Nd0.10Na0.06La0.02)Σ2.66(Mg0.94Mn0. 23Fe0.23Al0.03)Σ1.43(Zr2.75Ti0.96Th0.29)Σ4.00 [(Ba0.72Th0.26U0.02)Σ1.00(Nb9.23Ti2.29Ta0.36Si0.12)Σ12.00O42]·12H2O. The mineral is cubic, space group Im3̅ (204), a = 13.017(1) Å, V = 2206(1) Å3, Z = 2. Menezesite is isostructural with the synthetic compound Mg7[MgW12O42](OH)4·8H2O. The mineral was named in honor of Luiz Alberto Dias Menezes Filho (born 1950), mining engineer, mineral collector and merchant. Both the description and the name were approved by the CNMMN-IMA (Nomenclature Proposal 2005-023). Menezesite is the first natural heteropolyniobate. Heteropolyanions have been employed in a range of applications that include virus-binding inorganic drugs (including the AIDs virus), homogeneous and heterogeneous catalysts, electro-optic and electrochromic materials, metal and protein binding, and as building blocks for nanostructuring of materials.

Enxame de diques da junção tríplice do Paraná, Brasil meridional

This work intends primarily to survey the field, mineralogical and petrographic characters of the mafic dykes which occur on a stretch of 650 km along the Southeastern coast of Brazil, between the city of Sao Sebastiao, and the island of Santa Catarina. New chemical and geochronological data are also presented. The coastal dyke swarms are envisaged as the northern and southern arms of a plume-generated triple junction system centered on the Parana State coast, and related to the initial opening of the South Atlantic. Mafic magma intruded as dyke swarms along three directions: N-S (the southern arm, along the Parana-Santa Catarina coast), NW-SE (Ponta Grossa arch) and NE-SW (the northern arm along the Sao Paulo coast). Fifty two dykes, almost all tholeiitic diabases, were mapped and sampled along the south arm coast. The Ponta Grossa arch dykes are chiefly composed of tholeiitic diabases and lesser intrusions of andesitic to rhyolitic composition. Over 240 dykes were sampled and identified along the north arm west of Sao Sebastiao. Lamprophyres are here abundant, followed by diabases, microdiorite porphyries and lesser amounts of trachy-andesite, carbonatite and Precambrian dykes. Special attention was given to the study of lamprophyres, their field appearance relative abundance, mineral and chemical composition, enclaves and relations to neighboring alkaline intrusions.

Footemineite, the Mn-analog of atencioite, from the Foote mine, Kings Mountain, Cleveland County, North Carolina, U.S.A., and its relationship with other roscherite-group minerals

Abstract Footemineite, ideally Ca2Mn2+□Mn22+Mn22+Be4(PO4)6(OH)4·6H2O, triclinic, is a new member of the roscherite group. It occurs on thin fractures crossing quartz-microcline-spodumene pegmatite at the Foote mine, Kings Mountain, Cleveland County, North Carolina, U.S.A. Associated minerals are albite, analcime, eosphorite, siderite/rhodochrosite, fairfieldite, fluorapatite, quartz, milarite, and pyrite. Footemineite forms prismatic to bladed generally rough to barrel-shaped crystals up to about 1.5 mm long and 1 mm in diameter. Its color is yellow, the streak is white, and the luster is vitreous to slightly pearly. Footemineite is transparent and non-fluorescent. Twinning is simple, by reflection, with twin boundaries across the length of the crystals. Cleavage is good on {01̅1} and {100}. Density (calc.) is 2.873 g/cm3. Footemineite is biaxial (-), nα = 1.620(2), nβ = 1.627(2), nγ = 1.634(2) (white light). 2Vobs = 80°, 2Vcalc = 89.6°. Orientation: X ^ b ~ 12°, Y ^ c ~ 15°, Z ^ a ~ 15°. Elongation direction is c, dispersion: r > v or r < v, weak. Pleochroism: β (brownish yellow) > α = γ (yellow). Mössbauer and IR spectra are given. The chemical composition is (EDS mode electron microprobe, Li and Be by ICP-OES, Fe3+:Fe2+ by Mössbauer, H2O by TG data, wt%): Li2O 0.23, BeO 9.54, CaO 9.43, SrO 0.23, BaO 0.24, MgO 0.18, MnO 26.16, FeO 2.77, Fe2O3 0.62, Al2O3 0.14, P2O5 36.58, SiO2 0.42, H2O 13.1, total 99.64. The empirical formula is (Ca1.89Sr0.03Ba0.02)Σ1.94(Mn2+0.90□0.10)Σ1.00(□0.78Li0.17Mg0.05)Σ1.00(Mn2+3.25Fe2+0.43Fe3+0.09 Al0.03)Σ3.80Be4.30(P5.81Si0.08O24)[(OH)3.64(H2O)0.36]Σ4.00·6.00H2O. The strongest reflection peaks of the powder diffraction pattern [d, Å (I, %) (hkl)] are 9.575 (53) (010), 5.998 (100) (01̅1), 4.848 (26) (021), 3.192 (44) (210), 3.003 (14) (02̅2), 2.803 (38) (1̅03), 2.650 (29) (2̅02), 2.424 (14) (231). Single-crystal unit-cell parameters are a = 6.788(2), b = 9.972(3), c = 10.014(2) Å, α = 73.84(2), β = 85.34(2), γ = 87.44(2)°; V = 648.74 Å3, Z = 1. The space group is P1̅. Crystal structure was refined to R = 0.0347 with 1273 independent reflections (F > 2σ). Footemineite is dimorphous with roscherite, and isostructural with atencioite. It is identical with the mineral from Foote mine described as “triclinic roscherite.” The name is for the Foote mine, type locality for this and several other minerals.

Distribution, mineralogy, petrography, provenance and significance of Permian ash-carrying deposits in the Paraná Basin

Seccoes delgadas de testemunhos de sondagem e afloramentos no sul do Brasil demonstraram a ocorrencia de frequentes quedas de cinzas vulcânicas durante o Permiano entre 280 e 245 Ma. Minusculas (ca. 0,1mm) lascas de vidro vulcânico (glass shards) alterado, encontram-se dispersas ou concentradas nos sedimentos permianos das formacoes Rio Bonito e Tatui, na Bacia do Parana. O sedimento portador de glass shards e geralmente um lamito siltoso contendo em geral variavel quantidade de calcita calcrete. Restos vitreos soterrados foram substituidos por analcita ou mais raramente calcita, silica, zeolitas ou montmorilonita. Explosoes vulcânicas sao responsaveis por queda de cinzas em extensas areas, e por isso, um possivel vulcanismo permiano gerador foi procurado na Africa do Sul, na Cordilheira Andina e margens da Bacia do Parana. Foi proposta como fonte mais adequada deste vulcanismo um enxame de centros rioliticos descritos na Cordilheira Frontal e na Provincia Argentina de La Pampa (Patagonia). Nesta area os vulcoes devem ter expelido cinzas que caminharam milhares de quilometros antes de se depositarem e se preservarem em ambientes deltaicos ou marinhos rasos. Vinte e tres ocorrencias conhecidas de sedimentos permianos contendo glass shards foram locados em mapa da Bacia do Parana. Os relatos de ocorrencia deste tipo de sedimento sao gradualmente decrescentes para NE. Por esse motivo, os autores imaginam densas nuvens provindas da Patagonia e alcancando a Australia, depositando quantidades cada vez menores de material a medida que se deslocavam. Sedimentos com shards devem ser diferenciados dos tonsteins, ash falls e ash flows que tem sido tambem registradas no Gondwana permiano e que seriam indicadoras de fontes mais proximas.

Novos Dados Geológicos e Geofísicos para a Caracterização Geométrica e Estratigráfica da Sub-bacia de Alhandra (sudeste da Paraíba)

Some recent geological and geophysical reconnaissance studies carried out in the Alhandra Sub-basin (southern segment of the Paraiba Basin) have revealed very interesting structural and stratigraphic behaviors that have not yet been described. Four different structural compartments with NNE-SSW trends were identified, each characterized by a particular stratigraphic pile, as a result of vertical tectonic displacements, probably post-Pliocene in age: the Alto Rio Mumbaba High (with widespread basement outcrops), the Rio Mamuaba Graben (the well-exposed Beberibe Formation with thicknesses from 100 m up to 300 m), the Rio Gramame High (a horst zone, with some basement outcrops, underlying the Beberibe Formation) and the Alhandra-Guruji- Conde-Caapora monoclinal zone, east of the BR-101, limited to the west by a fault line. The stratigraphic sequence of the Paraiba basin represented by the Paraiba Group is complete only along the eastern monoclinal zone, where the Barreiras Group is also preserved. Along the Rio Mamuaba graben, occurrences of the Barreiras Group were not found as would be expected, and this seems to be an indication that more than one phase of vertical movement occurred, the second of which had probably removed the Barreiras Group. All these observations are preliminary and demand further geological and geophysical studies, especially at scales greater than 1/50.000

Bendadaite, a new iron arsenate mineral of the arthurite group

Abstract Bendadaite, ideally Fe2+Fe23+(AsO4)2(OH)2·4H2O, is a new member of the arthurite group. It was found as a weathering product of arsenopyrite on a single hand specimen from the phosphate pegmatite Bendada, central Portugal (type locality). Co-type locality is the granite pegmatite of Lavra do Almerindo (Almerindo mine), Linópolis, Divino das Laranjeiras county, Minas Gerais, Brazil. Further localities are the Veta Negra mine, Copiapó province, Chile; Oumlil-East, Bou Azzer district, Morocco; and Pira Inferida yard, Fenugu Sibiri mine, Gonnosfanadiga, Medio Campidano Province, Sardinia, Italy. Type bendadaite occurs as blackish green to dark brownish tufts (<0.1 mm long) and flattened radiating aggregates, in intimate association with an intermediate member of the scorodite-mansfieldite series. It is monoclinic, space group P21/c, with a = 10.239(3) Å, b = 9.713(2) Å, c = 5.552(2) Å, β = 94.11(2)º, V = 550.7(2) Å3, Z = 2. Electron-microprobe analysis yielded (wt.%): CaO 0.04, MnO 0.03, CuO 0.06, ZnO 0.04, Fe2O3 (total) 43.92, Al2O3 1.15, SnO2 0.10, As2O5 43.27, P2O5 1.86, SO3 0.03. The empirical formula is (Fe0.522+Fe0.323+⃞0.16)∑1.00(Fe1.893+Al0.11)∑2.00(As1.87P0.13)∑2.00O8(OH)2.00·4H2O, based on 2(As,P) and assuming ideal 8O, 2(OH), 4H2O and complete occupancy of the ferric iron site by Fe3+ and Al. Optically, bendadaite is biaxial, positive, 2Vest. = 85±4º, 2Vcalc. = 88º, with α 1.734(3), β 1.759(3), γ 1.787(4). Pleochroism is medium strong: X pale reddish brown, Y yellowish brown, Z dark yellowish brown; absorption Z > Y > X, optical dispersion weak, r > v. Optical axis plane is parallel to (010), with X approximately parallel to a and Z nearly parallel to c. Bendadaite has vitreous to sub-adamantine luster, is translucent and non-fluorescent. It is brittle, shows irregular fracture and a good cleavage parallel to {010}. Dmeas. 3.15±0.10 g/cm3, Dcalc. 3.193 g/cm3 (for the empirical formula). The five strongest powder diffraction lines [d in Å (I)(hkl)] are 10.22 (10)(100), 7.036 (8)(110), 4.250 (5)(111), 2.865 (4)(3̄11), 4.833 (3)(020,011). The d spacings are very similar to those of its Zn analogue, ojuelaite. The crystal structure of bendadaite was solved and refined using a crystal from the co-type locality with the composition (Fe0.952+⃞0.05)∑1.00(Fe1.803+Al0.20)∑2.00(As1.48P0.52)∑2.00O8(OH)2·4H2O (R = 1.6%), and confirms an arthurite-type atomic arrangement.

Waimirite-(Y), orthorhombic YF3, a new mineral from the Pitinga mine, Presidente Figueiredo, Amazonas, Brazil and from Jabal Tawlah, Saudi Arabia: description and crystal structure

Abstract Waimirite-(Y) (IMA 2013-108), orthorhombic YF3, occurs associated with halloysite, in hydrothermal veins (up to 30 mm thick) cross-cutting the albite-enriched facies of the A-type Madeira granite (~1820 Ma), at the Pitinga mine, Presidente Figueiredo Co., Amazonas State, Brazil. Minerals in the granite are ‘K-feldspar’, albite, quartz, riebeckite, ‘biotite’, muscovite, cryolite, zircon, polylithionite, cassiterite, pyrochlore-group minerals, ‘columbite’, thorite, native lead, hematite, galena, fluorite, xenotime-(Y), gagarinite-(Y), fluocerite-(Ce), genthelvite–helvite, topaz, ‘illite’, kaolinite and ‘chlorite’. The mineral occurs as massive aggregates of platy crystals up to ~1 μm in size. Forms are not determined, but synthetic YF3 displays pinacoids, prisms and bipyramids. Colour: pale pink. Streak: white. Lustre: non-metallic. Transparent to translucent. Density (calc.) = 5.586 g/cm3 using the empirical formula. Waimirite-(Y) is biaxial, mean n = 1.54-1.56. The chemical composition is (average of 24 wavelength dispersive spectroscopy mode electron microprobe analyses, O calculated for charge balance): F 29.27, Ca 0.83, Y 37.25, La 0.19, Ce 0.30, Pr 0.15, Nd 0.65, Sm 0.74, Gd 1.86, Tb 0.78, Dy 8.06, Ho 1.85, Er 6.38, Tm 1.00, Yb 5.52, Lu 0.65, O (2.05), total (97.53) wt.%. The empirical formula (based on 1 cation) is (Y0.69Dy0.08Er0.06Yb0.05Ca0.03Gd0.02Ho0.02Nd0.01Sm0.01Tb0.01Tm0.01Lu0.01)∑1.00[F2.54⃞0.25O0.21]∑3.00. Orthorhombic, Pnma, a = 6.386(1), b = 6.877(1), c = 4.401(1) Å, V = 193.28(7) Å3, Z = 4 (powder data). Powder X-ray diffraction (XRD) data [d in Å (I) (hkl)]: 3.707 (26) (011), 3.623 (78) (101), 3.438 (99) (020), 3.205 (100) (111), 2.894 (59) (210), 1.937 (33) (131), 1.916 (24) (301), 1.862 (27) (230). The name is for the Waimiri-Atroari Indian people of Roraima and Amazonas. A second occurrence of waimirite-(Y) is described from the hydrothermally altered quartz-rich microgranite at Jabal Tawlah, Saudi Arabia. Electron microprobe analyses gave the empirical formula (Y0.79Dy0.08Er0.05Gd0.03Ho0.02Tb0.01 Tm0.01Yb0.01)∑1.00[F2.85O0.08⃞0.07]∑3.00. The crystal structure was determined with a single crystal from Saudi Arabia. Unit-cell parameters refined from single-crystal XRD data are a = 6.38270(12), b = 6.86727(12), c = 4.39168(8) Å, V = 192.495(6) Å3, Z = 4. The refinement converged to R1 = 0.0173 and wR2 = 0.0388 for 193 independent reflections. Waimirite-(Y) is isomorphous with synthetic SmF3, HoF3 and YbF3. The Y atom forms a 9-coordinated YF9 tricapped trigonal prism in the crystal structure. The substitution of Y for Dy, as well as for other lanthanoids, causes no notable deviations in the crystallographic values, such as unit-cell parameters and interatomic distances, from those of pure YF3.

Matioliite‚ the Mg-analog of burangaite‚ from Gentil mine‚ Mendes Pimentel‚ Minas Gerais‚ Brazil‚ and other occurrences

Abstract Matioliite, ideally NaMgAl5(PO4)4(OH)6·2H2O, occurs as a secondary hydrothermal mineral in the Gentil mine granite pegmatite, Mendes Pimentel Co., Minas Gerais, Brazil. Some crystals are zoned to more Fe-rich compositions with an Fe2+:Mg ratio of approximately 1:1, corresponding to an intermediate member of the burangaite-matioliite solid-solution series. Matioliite is intimately associated with fluorapatite, crandallite, and zoned gormanite-souzalite cystals. The mineral forms prismatic to tabular crystals, up to 1 mm long. Matioliite is transparent and displays a vitreous luster; it is blue to colorless with a white streak. It is non-fluorescent. Mohs hardness is about 5. Calculated density is 2.948 g/cm3. Matioliite is biaxial negative, ηα = 1.597(2), ηβ = 1.627(2), ηγ = 1.632(1) (white light), 2V (meas.) = 43(2)°, 2V (calc.) = 44°, dispersion r > v, orientation X = b, Z ^ c = 6°. Pleochroism is Y > X > Z, X = light blue to colorless, Y = blue, Z = colorless. The empirical formula is (Na0.94Ca0.01)Σ0.95 (Mg0.88Fe2+0.11Mn0.01)Σ1.00(Al4.84Fe3+0.13)Σ4.97(PO4)4.03(OH)5.76·2H2O. The mineral is monoclinic, space group C2/c, a = 25.075(1) Å, b = 5.0470(3) Å, c = 13.4370(7) Å, β = 110.97(3)°, V = 1587.9(4) Å3, Z = 4. Crystal-structure determination was carried out and showed it is isostructural with burangaite, dufr énite, and natrodufrénite. Both the description and the name were approved by the CNMMN-IMA (Nomenclature Proposal 2005-011). The .magnesium analog of burangaite. described from the Gold Quarry mine, Carlin-trend, Eureka County, Nevada; “burangaite” from Hochgosch, Millstätter See-Rücken, Kärnten, Austria; and .burangaite. described from Córrego Pomarolli, Linópolis, Divino das Laranjeiras, Minas Gerais, Brazil, are probably matioliite.

Witzkeite: A new rare nitrate-sulphate mineral from a guano deposit at Punta de Lobos, Chile

Abstract Witzkeite, ideally Na4K4Ca(NO3)2(SO4)4·2H2O, is a new mineral found in the oxidation zone of the guano mining field at Punta de Lobos, Tarapacá region, Chile. It occurs as colorless, tabular crystals up to 140 μm in length, associated with dittmanite and nitratine. Witzkeite is colorless and transparent, with a white streak and a vitreous luster. It is brittle, with Mohs hardness 2 and distinct cleavage on {001}. Measured density is 2.40(2) g/cm3, calculated density is 2.403 g/cm3. Witzkeite is biaxial (-) with refractive indexes α = 1.470(5), β = 1.495(5), γ = 1.510(5), measured 2V = 50-70°. The empirical composition is (electron microprobe, mean of five analyses, H2O, CO2, and N2O5 by gas chromatography; wt%): Na2O 12.83, K2O 22.64, CaO 7.57, FeO 0.44, SO3 39.96, N2O5 12.7, H2O 4.5, total 100.64; CO2 was not detected. The chemical formula, calculated based on 24 O, is: Na3.40K3.95Ca1.11Fe0.05(NO3)1.93(SO4)4.10(H4.10O1.81). Witzkeite is monoclinic, space group C2/c, with unit-cell parameters: a = 24.902(2), b = 5.3323(4), c = 17.246(1) Å, β = 94.281(7)°, V = 2283.6(3) Å3 (Z = 4). The crystal structure was solved using single-crystal X-ray diffraction data and refined to R1(F) = 0.043. Witzkeite belongs to a new structure type and is noteworthy for the very rare simultaneous presence of sulfate and nitrate groups. The eight strongest X-ray powder-diffraction lines [d in Å (I in %) (h k l)] are: 12.38 (100) (2 0 0), 4.13 (19) (6 0 0), 3.10 (24) (8 0 0), 2.99 (7) (8̄ 0 2), 2.85 (6) (8 0 2), 2.69 (9) (7̅ 1 3), 2.48 (12) (10 0 0), and 2.07 (54) (12 0 0). The IR spectrum of witzkeite was collected in the range 390-4000 cm-1. The spectrum shows the typical bands of SO42- ions (1192, 1154, 1116, 1101, 1084, 993, 634, and 617 cm-1) and of NO3- ions (1385, 1354, 830, 716, and 2775 cm-1). Moreover, a complex pattern of bands related to H2O is visible (bands at 3565, 3419, 3260, 2405, 2110, 1638, and 499 cm-1). The IR spectrum is discussed in detail.

Mejillonesite, a new acid sodium, magnesium phosphate mineral, from Mejillones, Antofagasta, Chile

Abstract Mejillonesite, ideally NaMg2(PO3OH)(PO4)(OH)· H5O2, is a new mineral approved by the CNMNC (IMA 2010-068). It occurs as isolated crystal aggregates in thin zones in fine-grained opal-zeolite aggregate on the north slope of Cerro Mejillones, Antofagasta, Chile. Closely associated minerals are bobierrite, opal, clinoptilolite-Na, clinoptilolite-K, and gypsum. Mejillonesite forms orthorhombic, prismatic, and elongated thick tabular crystals up to 6 mm long, usually intergrown in radiating aggregates. The dominant form is pinacoid {100}. Prisms {hk0}, {h0l}, and {0kl} are also observed. The crystals are colorless, their streak is white, and the luster is vitreous. The mineral is transparent. It is non-fluorescent under ultraviolet light. Mohs’ hardness is 4, tenacity is brittle. Cleavage is perfect on {100}, good on {010} and {001}, and fracture is stepped. The measured density is 2.36(1) g/cm3; the calculated density is 2.367 g/cm3. Mejillonesite is biaxial (-), α = 1.507(2), β = 1.531(2), γ = 1.531(2), 2V (meas) = 15(10)°, 2V (calc) = 0° (589 nm). Orientation is X = a, Z = elongation direction. The mineral is non-pleochroic. Dispersion is r > v, medium. The IR spectrum contains characteristic bands of the Zundel cation (H5O2+, or H+·2H2O) and the groups P-OH and OH−. The chemical composition is (by EDS, H2O by the Alimarin method, wt%): Na2O 9.19, MgO 26.82, P2O5 46.87, H2O 19, total 101.88. The empirical formula, based on 11 oxygen atoms, is Na0.93Mg2.08(PO3OH)1.00(PO4)1.06(OH)0.86 · 0.95H5O2. The strongest eight X-ray powder-diffraction lines [d in Å(I)(hkl)] are: 8.095(100)(200), 6.846(9) (210), 6.470(8)(111), 3.317(5)(302), 2.959(5)(132), 2.706(12)(113), 2.157(19)(333), and 2.153(9) (622). The crystal structure was solved on a single crystal (R = 0.055) and gave the following data: orthorhombic, Pbca, a = 16.295(1), b = 13.009(2), c = 8.434(1) Å, V = 1787.9(4) Å3, Z = 8. The crystal structure of mejillonesite is based on a sheet (parallel to the b-c plane) formed by two types of MgO6 octahedra, isolated tetrahedra PO4 and PO3OH whose apical vertices have different orientation with respect to the sheet. The sheets are connected by interlayer, 5-coordinated sodium ions, proton hydration complexes, and hydroxyl groups. The structure of mejillonesite is related to that of angarfite, NaFe53+(PO4)4(OH)4·4H2O and bakhchisaraitsevite, Na2Mg5`(PO4)4·7H2O.