NIOBOHEFTETJERNITE, ScNbO4, A NEW MINERAL FROM THE BEFANAMO PEGMATITE, MADAGASCAR

2021 ◽  
Author(s):  
Inna Lykova ◽  
Ralph Rowe ◽  
Glenn Poirier ◽  
Andrew M. McDonald ◽  
Gerald Giester
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Chemical Composition ◽  
Diffraction Data ◽  
Empirical Formula ◽  
New Mineral ◽  
X Ray Diffraction ◽  
X Ray ◽  
Black Streak ◽  
Reflectance Data

ABSTRACT A new mineral, nioboheftetjernite, ideally ScNbO4, was found in the Befanamo pegmatite, Analamanga, Madagascar. It occurs as anhedral grains and very crude elongated crystals up to 200 μm in length in an intergrowth with rossovskyite, ilmenite, rutile, thortveitite, euxenite-(Y), feldspar, and quartz. The mineral is black with dark-brown to black streak and submetallic luster. It has no cleavage and its fracture is uneven. Dcalc is 5.855 g/cm3. The Raman spectrum and reflectance data are reported. The chemical composition (wt.%) is MgO 0.06, MnO 2.49, Fe2O3 12.14, Sc2O3 11.34, TiO2 5.94, SnO2 1.45, Nb2O5 32.23, Ta2O5 29.93, WO3 3.38, total 98.96. The empirical formula calculated on the basis of 4 O apfu is (Sc0.40Fe3+0.37Ti0.15Mn2+0.08)Σ1.00(Nb0.58Ta0.33W0.03Ti0.03Sn0.02)Σ0.99O4. The simplified general formula is (Sc,Fe3+)(Nb,Ta)O4. Nioboheftetjernite is monoclinic, P2/c, a = 4.7092(3), b = 5.6531(4), c = 5.0530(4) Å, β = 90.453(3)°, and V = 134.515(17) Å3. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are: 4.722(22)(100), 3.776(22)(011), 3.628(44)(110), , 2.938(83)(111), 2.472(30)(021), and . The crystal structure, refined from single-crystal X-ray diffraction data (R1 = 0.016), is of the “wolframite” type. The mineral is named as the Nb-analogue of heftetjernite, ScTaO4.

Ferroefremovite, (NH4)2Fe2+2(SO4)3, a new mineral from Solfatara di Pozzuoli, Campania, Italy

2020 ◽  
Author(s):  
Anatoly V. Kasatkin ◽  
Jakub Plášil ◽  
Radek Škoda ◽  
Italo Campostrini ◽  
Nikita V. Chukanov ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Chemical Composition ◽  
Electron Microprobe ◽  
Empirical Formula ◽  
New Mineral ◽  
Volcanic Complex ◽  
X Ray Diffraction ◽  
Cubic Crystals ◽  
X Ray ◽  
Mohs Hardness

ABSTRACT The new sulfate mineral ferroefremovite, ideally (NH4)2Fe2+2(SO4)3, was discovered at the “Bocca Grande” fumarole, Solfatara di Pozzuoli, Flegrean Volcanic Complex, Naples Province, Campania, Italy. Associated minerals are adranosite, adranosite-(Fe), godovikovite, huizingite-(Al), mascagnite, and opal. Ferroefremovite forms cubic crystals up to 0.1 mm across. The new mineral is colorless and has a vitreous luster and white streak. It is brittle and has an uneven fracture. No cleavage or parting are observed. Mohs hardness is 2. Dmeas. = 2.69(1) g/cm3. Dcalc. = 2.700 g/cm3. Optically, ferroefremovite is isotropic, n = 1.574(3) (λ = 589 nm). It is non-pleochroic. The presence of the NH4+ cation is confirmed by the Raman spectrum. The chemical composition of ferroefremovite is (wt.%; electron microprobe, N determined by CNH analysis) (NH4)2O 11.51, Na2O 0.11, K2O 1.35, MgO 8.38, MnO 0.98, FeO 18.94, SO3 57.08, total 98.35. The empirical formula based on 12 O apfu is [(NH4)1.85K0.12Na0.01]Σ1.98(Fe2+1.11Mg0.87Mn0.06)Σ2.04S2.99O12. Ferroefremovite is cubic, space group P213, with a = 10.0484(9) Å, V = 1014.59(16) Å3, and Z = 4. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are 5.80 (40) (111), 4.50 (20) (201, 210), 4.11 (30) (211), 3.17 (100) (310, 301), 3.02 (20) (311), 2.68 (50) (312, 321), 1.86 (18) (502, 432), 1.62 (18) (523, 532, 611).

Al analogue of chayesite from a lamproite of Cancarix, SE Spain, and its crystal structure

2020 ◽  
Vol 196 (3) ◽  
pp. 193-198
Author(s):  
Natalia V. Zubkova ◽  
Nikita V. Chukanov ◽  
Christof Schäfer ◽  
Konstantin V. Van ◽  
Igor V. Pekov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Empirical Formula ◽  
Structure Refinement ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
X Ray Diffraction ◽  
Se Spain ◽  
X Ray

Al analogue of chayesite (with Al > Fe3+) was found in a lamproite from Cancarix, SE Spain. The mineral forms green thick-tabular crystals up to 0.4 mm across in cavities. The empirical formula derived from EMP measurements and calculated on the basis of 17 Mg + Fe + Al + Si apfu is (K0.75 Na0.20 Ca0.11)Mg3.04 Fe0.99 Al1.18 Si11.80 O30. The crystal structure was determined from single crystal X-ray diffraction data ( R = 2.38%). The mineral is hexagonal, space group P 6/ mcc, a = 10.09199(12), c = 14.35079(19) Å, V = 1265.78(3) Å3, Z = 2. Fe is predominantly divalent. Al is mainly distributed between the octahedral A site and the tetrahedral T 2 site. The crystal chemical formula derived from the structure refinement is C (K0.73 Na0.16 Ca0.11)B (Na0.02)4 A(Mg0.42 Al0.29 Fe0.29)2 T 2(Mg0.71 Fe0.16 Al0.13)3 T 1(Si0.985 Al0.015)12 O30.

Shilovite, natural copper(II) tetrammine nitrate, a new mineral species

2015 ◽  
Vol 79 (3) ◽  
pp. 613-623 ◽  
Author(s):  
Nikita V. Chukanov ◽  
Sergey N. Britvin ◽  
Gerhard Möhn ◽  
Igor V. Pekov ◽  
Natalia V. Zubkova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Infrared Spectrum ◽  
Copper Complex ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
New Mineral Species ◽  
Mohs Hardness

AbstractThe new mineral shilovite, the first natural tetrammine copper complex, was found in a guano deposit located on the Pabellón de Pica Mountain, near Chanabaya, Iquique Province, Tarapacá Region, Chile. It is associated with halite, ammineite, atacamite (a product of ammineite alteration) and thénardite. The gabbro host rock consists of amphibole, plagioclase and minor clinochlore, and contains accessory chalcopyrite. The latter is considered the source of Cu for shilovite. The new mineral occurs as deep violet blue, imperfect, thick tabular to equant crystals up to 0.15 mm in size included in massive halite. The mineral is sectile. Its Mohs hardness is 2. Dcalc is 1.92 g cm–3. The infrared spectrum shows the presence of NH3 molecules and NO3– anions. Shilovite is optically biaxial (+), α = 1.527(2), β = 1.545(5), γ = 1.610(2). The chemical composition (electron-microprobe data, H calculated from ideal formula, wt.%) is Cu 26.04, Fe 0.31, N 30.8, O 35.95, H 4.74, total 100.69. The empirical formula is H12.56(Cu1.09Fe0.01)N5.87O6.00. The idealized formula is Cu(NH3)4(NO3)2. The crystal structure was solved and refined to R = 0.029 based upon 2705 unique reflections having F > 4σ(F). Shilovite is orthorhombic, space group Pnn2, a = 23.6585(9), b = 10.8238(4), c = 6.9054(3) Å, V = 1768.3(1) Å3, Z = 8. The strongest reflections of the powder X-ray diffraction pattern [d, Å (I,%) (hkl)] are: 5.931 (41) (400), 5.841 (100) (011), 5.208 (47) (410), 4.162 (88) (411), 4.005 (62) (420), 3.462 (50) (002), 3.207 (32) (031), 2.811 (40) (412).

Antipinite, KNa3Cu2(C2O4)4, a new mineral species from a guano deposit at Pabellón de Pica, Chile

2015 ◽  
Vol 79 (5) ◽  
pp. 1111-1121 ◽  
Author(s):  
Nikita V. Chukanov ◽  
Sergey M. Aksenov ◽  
Ramiza K. Rastsvetaeva ◽  
Konstantin A. Lyssenko ◽  
Dmitriy I. Belakovskiy ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Gas Chromatography ◽  
Chemical Composition ◽  
Infrared Spectrum ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
New Mineral Species ◽  
Mohs Hardness

AbstractThe new oxalate mineral antipinite is found in a guano deposit located on the Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile. Associated minerals are halite, salammoniac, chanabayaite, joanneumite and clays. Antipinite occurs as blue, imperfect, short prismatic crystals up to 0.1 mm × 0.1 mm × 0.15 mm in size, as well as their clusters and random aggregates. The mineral is brittle. Mohs hardness is 2; Dmeas = 2.53(3), Dcalc = 2.549 g cm–3. The infrared spectrum shows the presence of oxalate anions and the absence of absorptions associated with H2O molecules, C–H bonds, CO32–, NO3– and OH– ions. Antipinite is optically biaxial (+), α = 1.432(3), β = 1.530(1), γ = 1.698(5), 2Vmeas = 75(10)°, 2Vcalc = 82°. The chemical composition (electron-microprobe data, C measured by gas chromatography of products of ignition at 1200°C, wt.%) is Na2O 15.95, K2O 5.65, CuO 27.34, C2O3 48.64, total 99.58. The empirical formula is K0.96Na3.04Cu2.03(C2.00O4)4 and the idealized formula is KNa3Cu2(C2O4)4. The crystal structure was solved and refined to R = 0.033 based upon 4085 unique reflections with I > 2σ(I). Antipinite is triclinic, space group P1, a = 7.1574(5), b = 10.7099(8), c = 11.1320(8) Å, α = 113.093(1), β = 101.294(1), γ = 90.335 (1)°, V = 766.51(3) Å3, Z = 2. The strongest reflections of the powder X-ray diffraction pattern [d, Å (I,%) (hkl)] are 5.22 (40) (111), 3.47 (100) (032), 3.39 (80) (210), 3.01 (30) (033, 220), 2.543 (40) (122, 034, 104), 2.481 (30) (213), 2.315 (30) (143, 310), 1.629 (30) (146, 414, 243, 160).

Cuyaite, Ca2Mn3+As3+14O24Cl, a new mineral with an arsenite framework from near Cuya, Camarones Valley, Chile.

2020 ◽  
Vol 84 (3) ◽  
pp. 477-484
Author(s):  
Anthony R. Kampf ◽  
Stuart J. Mills ◽  
Barbara Nash ◽  
Maurizio Dini ◽  
Arturo A. Molina Donoso
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Meteoric Water ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
X Ray ◽  
Jahn Teller ◽  
Mohs Hardness ◽  
3D Framework

AbstractCuyaite (IMA2019-126), Ca2Mn3+As3+14O24Cl, is a new arsenite mineral from near Cuya in the Camarones Valley, Arica Province, Chile. It is associated with anhydrite, native arsenic, arsenolite, calcite, claudetite, ferrinatrite, gajardoite-3R, leiteite, magnesiocopiapite, phosphosiderite, pyrite, realgar and talmessite and formed from the oxidation of As-bearing primary phases and alteration by saline fluids derived from evaporating meteoric water under hyperarid conditions. Cuyaite occurs as pale brown thin needles (elongated on [010]), typically in divergent sprays and subparallel intergrowths. The streak is white. Crystals are transparent with adamantine lustre; subparallel intergrowths exhibit silky lustre. The mineral has Mohs hardness of 2½, is brittle, exhibits no cleavage and has irregular fracture. The calculated density is 4.140 g cm–3. Cuyaite is optically biaxial (–), with α = 1.87(1), β = 1.956(calc) and γ = 1.98(1), determined in white light; 2Vmeas = 60(1)°; and orientation: X = b and Y ^ a = 53° in obtuse β. Electron microprobe analyses provided the empirical formula Ca2.03Mn3+0.95(As3+13.66Sb3+0.65)Σ14.31O24Cl0.88. The six strongest powder X-ray diffraction lines are [dobs Å(I)(hkl)]: 4.73(45)(111, $\bar{1}$12), 3.162(100)($\bar{3}$14), 3.035(28)(213), 3.004(37)(204), 2.931(90)($\bar{2}$15, 312) and 2.779(28)(020). Cuyaite is monoclinic, Pn, a = 14.7231(6), b = 5.58709(19), c = 17.4185(12) Å, β = 112.451(8)°, V = 1324.23(14) Å3 and Z = 2. In the crystal structure of cuyaite (R1 = 0.0369 for 2095 I > 2σI reflections), AsO3 pyramids share O corners to form a ‘loose’ 3D framework; Jahn–Teller distorted Mn3+O6 octahedra and CaO8 polyhedra link by edges and corners to form columns; the columns also link by edge- and corner-sharing to the AsO3 pyramids in the framework; Cl occupies channels along [010] in the framework. The Raman spectrum is consistent with the presence of multiple As3+O3 groups.

Crystal structure and X-ray diffraction data of a new hexagonal perovskite compound, Ba4CuNb3O12

2011 ◽  
Vol 26 (3) ◽  
pp. 244-247
Author(s):  
N. Kumada ◽  
W. Zhang ◽  
Q. Dong ◽  
T. Mochizuki ◽  
Y. Yonesaki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Chemical Composition ◽  
Solid State ◽  
Diffraction Data ◽  
Solid State Reaction ◽  
Inert Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Barium Copper

A new barium copper niobate, Ba4CuNb3O12, was successfully prepared by high-temperature solid-state reaction in an inert atmosphere. Rietveld-refinement analysis of the XRD data of the compound showed that it has the 8H-type hexagonal perovskite structure with space group P63/mmc (#194), a = 5.830(1) Å, c = 19.123(1) Å, and chemical composition of Ba4Cu1.84Nb2.16O12-δ.

New arsenate minerals from the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. V. Katiarsite, KTiO(AsO4)

2016 ◽  
Vol 80 (4) ◽  
pp. 639-646 ◽  
Author(s):  
Igor V. Pekov ◽  
Vasiliy O. Yapaskurt ◽  
Sergey N. Britvin ◽  
Natalia V. Zubkova ◽  
Marina F. Vigasina ◽  
...  
Keyword(s):  
Raman Spectrum ◽  
Chemical Composition ◽  
Scoria Cone ◽  
Crystalline Material ◽  
Fissure Eruption ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Tolbachik Volcano

AbstractA new mineral katiarsite, ideally KTiO(AsO4), occurs in sublimates of the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with hatertite, bradaczekite, johillerite, yurmarinite, tilasite, arsmirandite, hematite, tenorite, As-bearing orthoclase, fluorophlogopite and aphthitalite. Katiarsite occurs as long prismatic to acicular, typically sword-like, crystals up to 3 μm×10μm×50 μm in size, and rarely up to 0.15 mm long. Crystal forms are {011}, {201}, {100} and {001}. Katiarsite is transparent, colourless, with a vitreous lustre. The mineral is brittle. Cleavage was not observed, the fracture is uneven. Dcalc is 3.49 g cm–3. Katiarsite is optically biaxial (+), α = 1.784(3), β = 1.792(3), γ = 1.870(5); 2Vobs is small. Orientation is X = b, Y = a, Z = c. The Raman spectrum is reported. The chemical composition (wt.%, electron-microprobe data) is K2O 18.98, Fe2O3 5.07, TiO2 27.49, As2O5 47.48, total 99.02. The empirical formula, calculated based on 5 O apfu, is K1.00 (Ti0.85Fe3+0.16)∑1.01 As1.02O5. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I)(hkl)] are 5.91(17)(110), 5.62(74)(011), 4.18(19)(202), 3.157(66) (013), 2.826(100)(221), 2.809(96)(022) and 2.704(19)(004). Katiarsite is orthorhombic, a = 13.174(4), b = 6.5635(10), c = 10.805(2) Å, V = 934.3(3) Å3, Z = 8, space group Pna21, by analogy with KTA, synthetic KTiO(AsO4), a notable non-linear optical crystalline material. The name of the mineral reflects its chemical composition, kalium titanyl arsenate.

Tetramethylammonium bifluoride, crystal structure and vibrational spectra

1989 ◽  
Vol 67 (11) ◽  
pp. 1898-1901 ◽  
Author(s):  
William W. Wilson ◽  
Karl O. Christe ◽  
Jin-an Feng ◽  
Robert Bau
Keyword(s):  
Crystal Structure ◽  
Raman Spectrum ◽  
Vibrational Spectra ◽  
Diffraction Data ◽  
Direct Methods ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Single crystals of [N(CH3)4]HF2 were obtained as a by-product during the recrystallization of [N(CH3)4]ClF4 from CH3CN solution. X-ray diffraction data show that [N(CH3)4]HF2 crystallizes in the orthorhombic space group Pmn21 with Z = 2 and unit cell dimensions a = 6.611(5), b = 8.753(5), and c = 5.386(4) Å. The structure was solved by direct methods and refined by least squares to a final R = 0.055 by using 205 independent reflections. The HF2− anions are symmetric, exhibit an unusually short [Formula: see text] distance of 2.213(4) Å, and vibrational frequencies close to those of the free HF2− anion. Keywords: tetramethylammonium bifluoride, crystal structure, Raman spectrum.

Carlosbarbosaite, ideally (UO2)2Nb2O6(OH)2·2H2O, a new hydrated uranyl niobate mineral with tunnels from Jaguaraçu, Minas Gerais, Brazil: description and crystal structure

2012 ◽  
Vol 76 (1) ◽  
pp. 75-90 ◽  
Author(s):  
D. Atencio ◽  
A. C. Roberts ◽  
M. A. Cooper ◽  
L. A. D. Menezes Filho ◽  
J. M. V. Coutinho ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Empirical Formula ◽  
Short Wave ◽  
Minas Gerais ◽  
New Mineral ◽  
X Ray Diffraction ◽  
Oh Groups ◽  
X Ray ◽  
Two Samples ◽  
Cavity Filling

AbstractCarlosbarbosaite, ideally (UO2)2Nb2O6(OH)2·2H2O, is a new mineral which occurs as a late cavity filling in albite in the Jaguaraçu pegmatite, Jaguaraçu municipality, Minas Gerais, Brazil. The name honours Carlos do Prado Barbosa (1917–2003). Carlosbarbosaite forms long flattened lath-like crystals with a very simple orthorhombic morphology. The crystals are elongated along [001] and flattened on (100); they are up to 120 μm long and 2–5 μm thick. The colour is cream to pale yellow, the streak yellowish white and the lustre vitreous. The mineral is transparent (as individual crystals) to translucent (massive). It is not fluorescent under either long-wave or short-wave ultraviolet radiation. Carlosbarbosaite is biaxial(+) with α = 1.760(5), β = 1.775(5), γ = 1.795(5), 2Vmeas. = 70(1)º, 2Vcalc. = 83º. The orientation is X || a, Y || b, Z || c. Pleochroism is weak, in yellowish green shades, which are most intense in the Z direction. Two samples were analysed. For sample 1, the composition is: UO3 54.52, CaO 2.07, Ce2O3 0.33, Nd2O3 0.49, Nb2O5 14.11, Ta2O5 15.25, TiO2 2.20, SiO2 2.14, Fe2O3 1.08, Al2O3 0.73, H2O (calc.) 11.49, total 104.41 wt.%; the empirical formula is (□0.68Ca0.28Nd0.02Ce0.02)Σ=1.00[U1.44□0.56O2.88(H2O)1.12](Nb0.80Ta0.52Si0.27Ti0.21Al0.11Fe0.10)Σ=2.01 O4.72(OH)3.20(H2O)2.08. For sample 2, the composition is: UO3 41.83, CaO 2.10, Ce2O3 0.31, Nd2O3 1.12, Nb2 O5 14.64, Ta2O5 16.34, TiO2 0.95, SiO2 3.55, Fe2O3 0.89, Al2O3 0.71, H2O (calc.) 14.99, total 97.43 wt.%; the empirical formula is (□0.67Ca0.27Nd0.05Ce0.01)Σ=1.00[U1.04□0.96O2.08(H2O)1.92] (Nb0.79Ta0.53Si0.42Ti0.08Al0.10Fe0.08)Σ=2.00O4.00(OH)3.96(H2O)2.04. The ideal endmember formula is (UO2)2Nb2O6(OH)2·2H2O. Calculated densities are 4.713 g cm-3 (sample 1) and 4.172 g cm-3 (sample 2). Infrared spectra show that both (OH) and H2O are present. The strongest eight X-ray powder-diffraction lines [listed as d in Å (I)(hkl)] are: 8.405(8)(110), 7.081(10)(200), 4.201(9)(220), 3.333(6)(202), 3.053(8)(022), 2.931(7)(420), 2.803(6)(222) and 2.589(5)(040,402). The crystal structure was solved using single-crystal X-ray diffraction (R = 0.037) which gave the following data: orthorhombic, Cmcm, a = 14.150(6), b = 10.395(4), c = 7.529(3) Å, V = 1107(1) Å3, Z = 4. The crystal structure contains a single U site with an appreciable deficiency in electron scattering, which is populated by U atoms and vacancies. The U site is surrounded by seven O atoms in a pentagonal bipyramidal arrangement. The Nb site is coordinated by four O atoms and two OH groups in an octahedral arrangement. The half-occupied tunnel Ca site is coordinated by four O atoms and four H2O groups. Octahedrally coordinated Nb polyhedra share edges and corners to form Nb2O6(OH)2 double chains, and edge-sharing pentagonal bipyramidal U polyhedra form UO5 chains. The Nb2O6(OH)2 and UO5 chains share edges to form an open U—Nb—φ framework with tunnels along [001] that contain Ca(H2O)4 clusters. Carlosbarbosaite is closely related to a family of synthetic U–Nb–ϕ framework tunnel structures, it differs in that is has an (OH)-bearing framework and Ca(H2O)4 tunnel occupant. The structure of carlosbarbosaite resembles that of holfertite.

Dyrnaesite-(La) a new hyperagpaitic mineral from the Ilímaussaq alkaline complex, South Greenland

2017 ◽  
Vol 81 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Jørn G. Rønsbo ◽  
Tonči Balić-Žunić ◽  
Ole V. Petersen
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Microprobe Analysis ◽  
Structural Formula ◽  
Accessory Mineral ◽  
New Mineral ◽  
Fracture Density ◽  
X Ray Diffraction ◽  
Alkaline Complex ◽  
X Ray

AbstractThe new mineral, dyrnaesite-(La), is found in the Ilímaussaq alkaline complex, South Greenland. The holotype material originates from an arfvedsonite lujavrite sheet as an accessory mineral. Dyrnaesite-(La) is pale yellowish green, with no cleavage and an irregular fracture. Density is 3.68(2)/3.682 g/cm3(measured/ calculated). It is biaxial, negative, 2Vα = 47(1)/48 (measured/calculated); α = 1.6226(5), β = 1.6852(10), γ = 1.6982(2);X=c,Y=a,Z=b. The average values of microprobe analyses are (wt.%) P2O537.17, SiO20.15, CaO 0.90, Na2O 20.06, La2O316.44, CeO220.23, Pr2O31.40, Nd2O33.47, Sm2O30.24, Dy2O30.06, Y2O30.06.The crystal structure was solved from single-crystal X-ray diffraction data. Dyrnaesite-(La) is orthorhombic,Pnma;a= 18.4662(7) Å,b= 16.0106(5) Å,c= 7.0274(2) Å,V= 2077.7(2) Å3,Z= 4. The structural formula calculated from the diffraction data and microprobe analysis is Na7.89(Ce0.94Ca0.06)∑1.00(Ca0.12La1.14Ce0.40Pr0.10Nd0.24)∑2.00(PO4)6, the simplified formula is Na8Ce4+REE2(PO4)6. The crystal structure is related closely to that of vitusite-(Ce), but is distinct from it in several aspects. The five strongest lines of the powder X-ray diffraction pattern are (d Å, (I %), (hkl)); 6.57 (100) (101), 4.62 (40) (301, 230, 400), 3.50 (40) (331), 2.80 (86) (232, 402), 2.67 (54) (060,630).

Sign in / Sign up

Export Citation Format

Share Document