Lanthanite-(Ce), (Ce,La,Nd)2(CO3)3 · 8H2O, a new mineral from Wales, U.K.
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Lanthanite-(Ce) occurs as a secondary mineral in oxidized copper ore at the Britannia Mine, Snowdoni4 North Wales, U.K. It is found as colorless transparent plates {010} covered by radiating tufts of malachite and is associated with brochantite, posnjakite and chalcoalumite. The analytical formula, based on t7 oxygens, is (Ce6.rrl-ao.rrNdo.rrSmo.oGdo.orYo.oohr.ouCz.rOg.ot'7.96H2O, and the theoretical formula is (Ce,La,Nd)r(CO3)3.8H2O with Ce > La,Nd. Orthorhombic, space goup Pbnb, a:9.482(6), b : 16.938(ll), c : 8.965(3)A,Z:4, D(calc.) :2.79 E/carr for the ideal formula (Ce:La:Nd : 0.83 :0.59 :0.58), D (meas .l : 2.76 g/cmt , V : 144043, a:brc :0.559E :1 :0.5293. Strongest lines in the X-ray powder diffraction pauern are ftlA (I) (hkl)l 8.47(100X020), 4.746(65)l2W),4.462(62NW2),3.255(73N202) and 3.028(65\222\. The mineral is biaxial negative, a 1.532(2), P 1.594(2),y l.6lQ2); orientation X:b, Y:c, Z:a;2V(measJ:60(2)0, 2V(calc.)=62,no dispersion observed. The mineral is not fluorescent, and has H:2.5, a colorless streak, a vitreous luster and is sectile. In dilute mineral acids (HCl, HNO.), the mineral reacts with effervescence to yield a gel-like precipitate oflanthanide(Ill) hydroxides.Keywords:
Malachite
Orthorhombic crystal system
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Phlogopite
Scheelite
Rare-earth element
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Abstract Kihlmanite-(Ce), Ce 2 TiO 2 [SiO 4 ](HCO 3 ) 2 (H 2 O), is a new rare-earth titanosilicate carbonate, closely related to tundrite-(Ce). It is triclinic, P , a = 4.994(2), b = 7.54(2), c = 15.48(4) Å, α = 103.5(4), β = 90.7(2), γ = 109.2(2) o , V = 533(1) Å 3 , Z = 2 (from powder diffraction data) or a = 5.009(5), b = 7.533(5), c = 15.407(5) Å, α = 103.061(5), β = 91.006(5), γ = 109.285(5)°, V = 531.8(7) Å 3 , Z = 2 (from single-crystal X-ray diffraction data). The mineral was found in the arfvedsonite-aegirine-microcline vein in fenitized metavolcanic rock at the foot of the Mt Kihlman (Chil’man), near the western contact of the Devonian Khibiny alkaline massif and the Proterozoic Imandra-Varzuga greenstone belt. It forms brown spherulites (up to 2 cm diameter) and sheaf-like aggregates of prismatic crystals, flattened on {010} and up to 0.5 mm diameter. Both spherulites and aggregates occur in interstices in arfvedsonite and microcline, in intimate association with golden-green tundrite-(Ce). Kihlmanite-(Ce) is brown, with a vitreous lustre and a pale yellowish-brown streak. The cleavage is perfect on {010}, parting is perpendicular to c and the fracture is stepped. Mohs hardness is ∼3. In transmitted light, the mineral is yellowish brown; pleochroism and dispersion were not observed. Kihlmanite-(Ce) is biaxial (+), α = 1.708(5), β = 1.76(1), γ = 1.82(1) (589 nm), 2 V calc = 89°. The optical orientation is Y ^ c = 5°, other details are unclear. The calculated and measured densities are 3.694 and 3.66(2) g cm −3 , respectively. The mean chemical composition, determined by electron microprobe, is: Na 2 O 0.13, Al 2 O 3 0.24, SiO 2 9.91, CaO 1.50, TiO 2 11.04, MnO 0.26, Fe 2 O 3 0.05, Nb 2 O 5 2.79, La 2 O 3 12.95, Ce 2 O 3 27.33, Pr 2 O 3 2.45, Nd 2 O 3 8.12, Sm 2 O 3 1.67, Gd 2 O 3 0.49 wt.%, with CO 2 15.0 and H 2 O 6.0 wt.% (determined by wet chemical and Penfield methods, respectively), giving a total of 99.93 wt.%. The empirical formula calculated on the basis of Si + Al = 1 atom per formula unit is (Ca 0.16 Na 0.11 Mn 0.02 )∑ 0.29 [(Ce 0.98 La 0.47 Pr 0.09 Nd 0.29 Sm 0.06 Gd 0.02 ) ∑1.91 (Ti 0.82 Nb 0.12 ) ∑0.94 O 2 (Si 0.97 Al 0.03 ) ∑1 O 4.02 (HCO 3 ) 2.01 ](H 2 O) 0.96 . The simplified formula is Ce2TiO2(SiO4)(HCO3)2·H2O. The mineral reacts slowly in cold 10% HCl with weak effervescence and fragmentation into separate plates. The strongest X-ray powder-diffraction lines [listed as d in Å( I ) ( hkl )] are as follows: 15.11(100)(00 ), 7.508(20)(00 ), 6.912(12)(0 1), 4.993(14)(00 ), 3.563(15)(0 1), 2.896(15)(1 ). The crystal structure of kihlmanite-(Ce) was refined to R 1 = 0.069 on the basis of 2441 unique observed reflections (Mo K α, 293 K). It is closely related to the crystal structure of tundrite-(Ce) and is based upon [Ce 2 TiO 2 (SiO 4 )(HCO 3 ) 2 ] layers parallel to (001). Kihlmanite-(Ce) can be considered as a cationdeficient analogue of tundrite-(Ce). The mineral is named in honour of Alfred Oswald Kihlman (1858–1938), a remarkable Finnish geographer and botanist who participated in the Wilhelm Ramsay expeditions to the Khibiny Mountains in 1891–1892. The mineral name also reflects its occurrence at the Kihlman (Chil’man) Mountain.
Pleochroism
Microcline
Nepheline
Aegirine
Triclinic crystal system
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Abstract Decrespignyite-(Y) is a new copper yttrium rare earth carbonate chloride hydrate from the Paratoo copper mine, near Yunta, Olary district, South Australia. Decrespignyite-(Y) occurs as blue crusts, coatings and fillings in thin fissures on the slatey country rock. Individual pseudohexagonal platelets are typically 10–50 µm in maximum dimension and are often curved. Associated minerals include caysichite-(Y), donnayite-(Y), malachite and kamphaugite-(Y). Electron microprobe and CHN analyses gave: Y 2 O 3 42.2; La 2 O 3 0.1; Pr 2 O 3 0.1; Nd 2 O 3 1.3; Sm 2 O 3 1.0; Gd 2 O 3 4; Tb 2 O 3 0.4; Dy 2 O 3 3.7; Ho 2 O 3 2.6; Er 2 O 3 2.5; CaO 0.5; CuO 10.9; Cl 3.0; CO 2 19.8; H 2 O 10.8, yielding an empirical formula of (Y 3.08 Gd 0.22 Dy 0.16 Ho 0.11 Er 0.10 Nd 0.06 Sm 0.05 Tb 0.02 La 0.02 Pr 0.01 Ca 0.08 ) ∑3.91 Cu 1.12 (CO 3 ) 3.70 -Cl 0.7 (OH) 5.79 ·2.4H 2 O. The simplified formula is (Y, REE ) 4 Cu(CO 3 ) 4 Cl(OH) 5 ·2H 2 O. The mineral is royal blue to turquoise-blue in colour, transparent, with a pearly to vitreous lustre and a pale blue streak. No cleavage was observed but the morphology suggests that cleavage would be on [010]. The Mohs' hardness is estimated to be 4. The strongest lines in the X-ray powder pattern are { d obs ( I obs ) ( hkl )} 22.79 (30) (010); 7.463 (30) (001); 7.086 (50) (011); 6.241 (100) (021); 4.216 (30) ( 12); 3.530 (40) (022); 3.336 (30) (032); 2.143 (30) (222, 01). The powder diffraction pattern was indexed on a monoclinic cell with a = 8.899(6), b = 22.77(2), c = 8.589(6)Å, β = 120.06(5)°, V = 1506.3(7) Å 3 and Z = 4. The structure of the new mineral could not be determined but powder diffraction data indicate the space group is P 2, P m or P 2/ m . The measured density is 3.64(2) g/cm 3 and the calculated density is 3.645 g/cm 3 . Decrespignyite-(Y) is biaxial negative with α = 1.604(4) and γ = 1.638(3) with β very close to γ pleochroism is medium strong; X very pale bluish, Y and Z bluish (with greenish tint). Decrespignyite-(Y) is a supergene mineral which precipitated from mildly basic carbonated ground waters. The mineral is named after Robert Champion de Crespigny, a prominent figure in the Australian mining industry and chancellor of the University of Adelaide.
Malachite
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Carlgieseckeite-(Nd), ideally NaNdCa 3 (PO 4 ) 3 F, a new mineral species of the belovite group of the apatite supergroup, was found at the Kuannersuit Plateau, Ilimaussaq alkaline complex, South Greenland. It is associated with albite, analcime and fluorapatite in cavities of an albite vein cross-cutting augite syenite. Carlgieseckeite-(Nd) forms hexagonal tabular crystals up to 0.25 × 1 × 1.3 mm, and their parallel intergrowth up to 0.7 × 1.3 mm is found epitactically overgrown on prismatic crystals of fluorapatite. A phase with the idealized formula Na 1.5 Nd 1.5 Ca 2 (PO 4 ) 3 F epitactically overgrows some crystals of carlgieseckeite-(Nd). Carlgieseckeite-(Nd) is transparent and shows a distinct color-change effect, from almost colorless with a greenish hue in daylight to pink in yellow electric light. The luster is vitreous. The Mohs hardness is ca . 5. The mineral is brittle with no observed cleavage and an uneven fracture. The calculated density is 3.91 g/cm 3 . Carlgieseckeite-(Nd) is optically negative, uniaxial [ω = 1.655(3), ɛ = 1.632(2)] or shows anomalous biaxiality [α 1.632(2), β 1.654(3), γ 1.656(3), 2 V (meas.) 15(5)°]. The average chemical composition (electron-microprobe data) is: Na 2 O 5.68, CaO 18.53, SrO 7.55, BaO 0.14, La 2 O 3 1.32, Ce 2 O 3 10.60, Pr 2 O 3 2.62, Nd 2 O 3 15.08, Sm 2 O 3 2.89, Gd 2 O 3 0.52, SiO 2 0.56, P 2 O 5 32.72, F 2.80, Cl 0.06, −O=(F,Cl) 2 −1.19, total 99.88 wt.%. The empirical formula calculated on the basis of 13 O + F + Cl apfu is: Na 1.17 Ca 2.11 Sr 0.46 Ba 0.01 La 0.05 Ce 0.41 Pr 0.10 Nd 0.57 Sm 0.11 Gd 0.02 Si 0.06 P 2.94 O 12.05 F 0.94 Cl 0.01 . Carlgieseckeite-(Nd) is trigonal, space group P 3, a 9.4553(1), c 6.9825(1) A, V 540.62(1) A 3 , Z = 2. The crystal structure was refined from X-ray-diffraction data (single crystal, R = 0.0218). Carlgieseckeite-(Nd) is the isostructural Ca- and Nd-dominant analogue of belovite-(Ce) and belovite-(La). The strongest lines of the powder X-ray pattern [ d in A ( I )( hkl )] are: 7.02(22)(001), 5.33(18)(101), 3.923(27)(111), 3.463(23)(002), 3.095(19)(210), 2.815(100)(211,112), 2.727(42)(300). The mineral is named in honor of Carl Ludwig Giesecke (1761–1833), a mineralogist and polar explorer, the pioneer researcher of the mineralogy of Greenland. The Levinson suffix modifier -(Nd) is appropriate to express the dominance of Nd over other REE in the mineral. The holotype material is deposited in the Fersman Mineralogical Museum of Russian Academy of Sciences, Moscow.
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Lecoqite-(Y), ideally Na 3 Y(CO 3 ) 3 ·6H 2 O, a new mineral species, was discovered at the Poudrette quarry, Mont Saint-Hilaire, Quebec, Canada. It is associated with microcline, albite, natrolite, gonnardite, aegirine, siderite, elpidite, gaidonnayite, zircon, franconite, dawsonite, rhodochrosite, cryolite, rutile, and sphalerite. Lecoqite-(Y) forms radiating, spray-like aggregates in compact, tightly packed masses to 2.5 cm across, composed of flexible, extremely thin, capillary crystals up to 2.5 cm long and up to 0.01 mm thick. Individuals are colorless, and aggregates are white. The luster is strikingly silky. D(calc.) = 2.358 g/cm 3 . Lecoqite-(Y) is optically uniaxial positive, ω = 1.521(3), e = 1.497(3). The IR spectrum is unique. The chemical composition (electron microprobe, H 2 O by modified Penfield method, CO 2 by selective absorption, average results) is: Na 2 O 19.22, CaO 0.03, Y 2 O 3 17.95, Nd 2 O 3 0.54, Sm 2 O 3 0.41, Gd 2 O 3 0.75, Dy 2 O 3 3.31, Ho 2 O 3 1.12, Er 2 O 3 3.20, Yb 2 O 3 1.48, CO 2 27.0, H 2 O 23.4, total 98.41 wt.%. The empirical formula calculated for 15 O apfu is: Na 2.94 (Y 0.755 Dy 0.085 Er 0.08 Yb 0.035 Ho 0.03 Gd 0.02 Nd 0.015 Sm 0.01 ) ∑1.03 (CO 3 ) 2.91 (OH) 0.21 (H 2 O) 6.06 . Lecoqite-(Y) is hexagonal, P 6 3 , a 11.316(4), c 5.931(2) A, V 657.7(4) A 3 , Z = 2. The crystal structure was established from X-ray powder data by the Rietveld method, based on the model of the isostructural synthetic Ln-free carbonate Na 3 Y(CO 3 ) 3 ·6H 2 O. Final agreement factors are: R p = 0.0468, R wp = 0.0657, R Bragg = 0.0343, R F = 0.0356. No mineral is closely related to lecoqite-(Y) in terms of structure. In the structure of lecoqite-(Y), REE atoms (REE = Y + Ln) are surrounded by six O atoms of CO 3 groups and three H 2 O molecules to form a tricapped triangular prism. The Na atoms are centered in distorted octahedra [NaO 4 (H 2 O) 2 ], which link to form infinite corrugated chains along c . The strongest five lines of the X-ray powder pattern [ d in A (I)( hkl )] are: 9.82(57)(100), 5.081(100)(101), 3.779(39)(201), 2.627(39)(112), 2.471(37)(131). Lecoqite-(Y) is named in memory of P.E. Lecoq de Boisbaudran (1838–1912), outstanding French chemist and specialist in the spectroscopic analysis of minerals and synthetic compounds, who made a great contribution to the chemistry of the rare-earth elements. The Levinson suffix modifier -(Y) is in line with the dominance of yttrium over other rare-earth elements in the mineral. The cotype specimens are deposited in the Fersman Mineralogical Museum of Russian Academy of Sciences, Moscow, and the Canadian Museum of Nature, Ottawa.
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Orthojoaquinite-(La) from Ilimaussaq, Greenland, is a new member of the joaquinite group. Its description was published by Semenov et al. (1967); although the chemical analytical data indicated that La is the dominant REE in the mineral, its true position in the group was not established for a third of a century. Orthojoaquinite-(La) is orthorhombic, probable space-group Ccmm, a 10.539(10), b 9.680(5), c 22.345(10) A, V 2280 A 3 , Z = 4. Chemical analytical data are: Na 2O 2.41, K2O 0.22, CaO (+SrO) 0.03, MnO 0.70, FeO 4.78, BaO 21.46, Fe2O3 0.39, La2O3 10.05, Ce2O3 9.40, Pr2O3 0.99, Nd2O3 2.15, SiO2 33.82, TiO2 9.20, ThO2 0.38, Nb2O5 2.31, H2O 1.50, F 0.38, sum 100.17, less O = F 0.16, total 100.01 wt.%. The empirical formula (based on O + OH + F + H2O = 28) is: (Ba1.99Ca0.01)� 2.00(Na1.11K0.07)� 1.18(La0.88Ce0.81Nd0.18Pr0.09)� 1.96 (Fe 2+ 0.95Mn0.14)� 1.09 (Ti1.64Nb0.25Fe 3+ 0.07 Th0.02)� 1.98 Si8.01O26.00[(OH)0.37O0.35F0.28]� 1.00•1.00H2O. The simplified formula is Ba2Na(La,Ce)2Fe 2+ Ti2Si8O26(OH,O,F)•H 2O. The mineral is brown, has a silky luster, and is transparent. The Mohs hardness is about 5 (VHN 350–430 kg/mm 2 ); it has a good {001} cleavage. The measured density is 4.1 g/cm 3 , and the calculated density is 4.14 g/cm 3 . Optical data: optically biaxial (+), � 1.754, � 1.760, � 1.797; 2V(meas.) 40°, 2V(calc.) 45°; orientation Z = c; pleochroism strong in yellow-green, Z > X.
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Pleochroism
Orthorhombic crystal system
Tremolite
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Bussyite-(Ce), ideally (Ce,REE,Ca) 3 (Na,H 2 O) 6 MnSi 9 Be 5 (O,OH) 30 (F,OH) 4 , a new mineral species, was found in the Mont Saint-Hilaire quarry, Quebec. The crystals are transparent to translucent, pale pinkish orange in color, with a white streak and vitreous luster. Bladed crystals are prismatic, having forms {111} and {101}; they are elongate on [101], up to 10 mm in length. Associated minerals include aegirine, albite, analcime, ancylite-(Ce), calcite, catapleiite, gonnardite, hydrotalcite, kupletskite, leucophanite, microcline, nenadkevichite, polylithionite, serandite and sphalerite. Bussyite-(Ce) is monoclinic, space group C 2/ c , with unit-cell parameters refined from powder-diffraction data: a 11.654(3), b 13.916(3), c 16.583(4) A, β 95.86(2)°, V 2675.4(8) A 3 and Z = 4. Electron-microprobe and secondary-ion mass spectrometric analyses give the average and ranges: Na 2 O 7.63 (9.40–6.62), K 2 O 0.05 (0.13–0.0), BeO 8.33 (SIMS), CaO 5.35 (5.95–4.17), MgO 0.03 (0.11–0.00), MnO 2.49 (3.00–1.71), Al 2 O 3 0.82 (1.54–0.39), Y 2 O 3 1.97 (2.68–1.51), La 2 O 3 2.65 (3.11–2.16), Ce 2 O 3 9.77 (11.22–8.15), Pr 2 O 3 1.23 (1.49–0.74), Nd 2 O 3 4.54 (5.13–3.91), Sm 2 O 3 0.99 (1.25–0.68), Eu 2 O 3 0.010 (0.25–0.0), Gd 2 O 3 1.03 (1.23–0.81), SiO 2 38.66 (39.94–37.66), ThO 2 3.31 (4.59–2.12), F 3.67 (6.39–2.54), S 0.03 (0.08–0), H 2 O 4.12 (determined from crystal-structure analysis), for a total of 95.21 wt.%. The empirical formula based on the crystal-structure analysis, ideally showing 34 anions, is: 4{(Ce 0.823 Nd 0.373 Y 0.242 Th 0.173 Pr 0.103 Sm 0.079 Gd 0.078 Eu 0.008 ) ∑1.879 (Ca 0.775 La 0.225 ) ∑1 [Na 3.000 (H 2 O) ∑2.500 Ca 0.544 K 0.015 ] ∑6.055 (Mn 0.485 Na 0.402 Mg 0.012 ) ∑0.899 (Si 8.897 Be 4.605 Al 0.222 ) ∑13.724 O 30 [F 2.67 (OH) 1.33 ] ∑4 }. The structure has been refined to an R index of 4.0% for 1134 unique, observed reflections. The structure has two chemically distinct layers parallel to (101): (1) a layer of [(Si,Be)O 4 ] tetrahedra, and (2) a layer of Ce–, Ca–, Mn–, Na–(O,F) polyhedra. Layers are cross-linked through shared O and F atoms. Significant amounts of OH and H 2 O are present, as indicated in the IR spectrum and crystal-structure analysis for the Na-poor hydrated phase. One instance of a rarer Na-rich phase is observed. Based on the electron-microprobe data, the formula for the rarer Na-rich anhydrous phase is 4{(Ce 1.047 Nd 0.466 La 0.323 Y 0.306 Pr 0.131 Sm 0.102 Gd 0.084 Eu 0.009 Th 0.042 ) ∑2.510 (Na 6.645 Ca 0.701 ) ∑7.346 (Si 9.521 Be 4.772 ) ∑14.293 O 29.251 F 4.749 }. Comparing the structure of bussyite-(Ce) to that of other beryllium silicates, the topology of the layer of tetrahedra most strongly resembles that of semenovite-(Ce) and the closely related mineral harstigite.
Microcline
Aegirine
Orthorhombic crystal system
Analcime
Monoclinic crystal system
Orthoclase
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Allanite
Paragenesis
Andradite
Diffractometer
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