Raman spectra of lucasite-(Ce), La-analogue of lucasite, kassite and cafetite are significantly different. Most evident differences were revealed in the position of bands corresponding to vibrational modes for bands assigned to symmetrical v1(Ti-O) and asymmetrical v3(O-Ti-O) stretching vibrations, as well as the bands determined by asymmetrical bending vibrations v4(transTiO6) and asymmetrical v3(O-Ti-O) stretching vibrations. Raman spectra of lucasite-(Ce) and La-analogue of lucasite are published for the first time. The presented data are valuable for the identification of cafetite and kassite group minerals using Raman spectroscopy.
The crystal structure of sergeysmirnovite, MgZn2(PO4)2·4H2O (orthorhombic, Pnma, a = 10.6286(4), b = 18.3700(6), c = 5.02060(15) Å, V = 980.26(6) Å3, Z = 4), a new member of the hopeite group of minerals, was determined and refined to R1 = 0.030 using crystals from the Këster mineral deposit in Sakha-Yakutia, Russia. Similar to other members of the hopeite group, the crystal structure of sergeysmirnovite is based upon [Zn(PO4)]– layers interlinked via interstitial [MO2(H2O)4]2– octahedra, where M = Mg2+. The layers are parallel to the (010) plane. Within the layer, the ZnO4 tetrahedra share common corners to form chains running along [001]. Sergeysmirnovite is a dimorph of reaphookhillite, a mineral from the Reaphook Hill zinc deposit in South Australia. The relations between sergeysmirnovite and reaphookhillite are the same as those between hopeite and parahopeite. Topological and structural complexity analysis using information theory shows that the hopeite (sergeysmirnovite) structure type is more complex, both structurally and topologically, than the parahopeite (reaphookhillite) structure type. Such complexity relations contradict the general observation that more complex polymorphs possess higher physical density and higher stability, since parahopeite is denser than hopeite. It could be hypothesized that hopeite is metastable under ambient conditions and separated from parahopeite by a structural and topological reconstruction that requires an essential energy barrier that is difficult to overcome.
Eliseevite, Na1.5Li[Ti2Si4O12.5(OH)1.5]∙2H2O, is a new microporous titanosilicate of the lintisitekukisvumite family [monoclinic, C2/c, a = 27.48(1), b = 8.669(4), c = 5.246(2) Å, β = 90.782(8)°, V = 1249.7(9) Å3, Z = 4]. The mineral is found in two different peralkaline veins in an ijolite-foyaite- malignite differentiated complex of the Lovozero alkaline massif, Kola Peninsula, Russia. At Mt. Alluaiv, eliseevite occurs in an aegirine-eudialyte-sodalite-microcline vein as long-prismatic to fibrous crystals (up to 2 mm long) growing in voids of natrolitized sodalite in close association with albite, analcime, catapleiite, chabazite-Ca, gmelinite-K, manganoneptunite, microcline, murmanite, and an ussingite. At Mt. Punkaruaiv, it is found within a ussingite-aegirine-microcline vein as longprismatic crystals (up to 0.8 mm long) in close association with chabazite-Ca, chkalovite, eudialyte, manganoneptunite, punkaruaivite, rhabdophane-(Ce), sodalite, sphalerite, and steenstrupine-(Ce). It is a late-stage, hydrothermal mineral formed as a result of alteration of murmanite. The mineral is transparent, pale creamy to colorless, with a vitreous luster and a white streak. Cleavage is perfect along {100}, fracture is splintery. Mohs hardness is about 5. In transmitted light, the mineral is colorless, biaxial (-): α = 1.665(2), β = 1.712(2), γ = 1.762(5) (for λ = 589 nm); Y = b, Z^a = 8-12°. Dispersion is medium, r < v. Dcalc = 2.706 g/cm3, Dmeas = 2.68(4) g/cm3. The mean chemical composition (n = 7) determined by the Penfield method (water), ICP-MS (Li), and electron microprobe (other elements) is (wt%): H2O 10.50, Li2O 2.85, Na2O 9.15, K2O 0.08, CaO 0.05, Fe2O3 0.21, Al2O3 0.08, SiO2 46.87, TiO2 29.40, Nb2O5 0.72, total 99.91. The empirical formula calculated on the basis of Si = 4 apfu is: (Na1.51K0.01Ca0.01)Σ1.53Li0.98[(Ti1.89Nb0.03Fe3+0.01Al0.01)Σ1.94Si4O12.26(OH)1.74]∙2.12H2O. The simplified formula taking into account the results of a single-crystal study is Na1.5Li{Ti2O2[Si4O10.5(OH)1.5]}∙2H2O. The six strongest reflections in the X‑ray powder-diffraction pattern [d in Å, (I), (hkl)] are: 13.76(100) (200), 6.296(60)(310), 3.577(80)(710), 3.005(70)(421), 2.881(70)(910), 2.710(50)(621). The mineral is named in honor of Nikolai Aleksandrovich Eliseev (1897-1966), a remarkable Russian geologist and petrologist, Professor at Leningrad State University, for his contributions to the geology and petrology of metamorphic and alkaline complexes.
Abstract Whiteite-(CaMnMn), CaMnMn 2 Al 2 [PO 4 ] 4 (OH) 2 ·8H 2 O, is a new hydrous phosphate of Ca, Mn and Al, which is closely related to both jahnsite-(CaMnMn) and the minerals of the whiteite group. It is monoclinic, P 2/ a , with a = 15.02(2), b = 6.95(1), c =10.13(3) Å, β = 111.6(1)°, V = 983.3(6) Å 3 , Z = 2 (from powder diffraction data) or a = 15.020(5), b = 6.959(2), c = 10.237(3) Å, β = 111.740(4)°, V = 984.3(5) Å 3 , Z = 2 (from single-crystal diffraction data). The mineral was found in the Hagendorf Süd granitic pegmatite (Germany) as small (up to 0.5 mm in size) crystals elongated on a and tabular on {010}. The crystals are either simply or polysynthetically twinned on {001}. They crystallize on the walls of voids within altered zwieselite crystals or form coronas (up to 1 mm in diameter) around cubic crystals of uraninite. The mineral is transparent, colourless to pale yellow (depending on Al–Fe 3+ substitution), with a vitreous lustre and a white streak. The cleavage is perfect on {001}, the fracture is stepped and the Mohs hardness is 3½. In transmitted light, the mineral is colourless; dispersion was not observed. Whiteite-(CaMnMn) is biaxial (+), α = 1.589(2), β = 1.592(2), γ = 1.601(2) (589 nm), 2V meas = 60(10)°, 2V calc = 60.3°. The optical orientation is X = b , Z^ a = 5°. The calculated and measured densities are D calc = 2.768 and D meas = 2.70(3) g cm –3 , respectively. The mean chemical composition determined by electron microprobe is Na 2 O 0.53, MgO 0.88, Al 2 O 3 11.66, P 2 O 5 34.58, CaO 4.29, MnO 17.32, FeO 8.32, ZnO 2.60 wt.%, with H 2 O 19.50 wt.% (determined by the Penfield method), giving a total of 99.68 wt.%. The empirical formula calculated on the basis of four phosphorus atoms per formula unit, with ferric iron calculated to maintain charge balance, is (Ca 0.63 Zn 0.26 Na 0.14 ) Σ1.03 (Mn 0.60 Fe 0.40 2+ ) Σ1.00 (Mn 1.40 Fe 0.37 2+ Mg 0.18 Fe 0.06 3+ ) Σ2.01 (Al 1.88 Fe 0.12 3+ ) Σ2.00 [PO 4 ] 4 (OH) 2 ·7.89H 2 O. The simplified formula is CaMnMn 2 Al 2 [PO 4 ] 4 (OH) 2 ·8H 2 O. The mineral is easily soluble in 10% HCl at room temperature. The strongest X-ray powder-diffraction lines [listed as d in Å (I) (hkl)] are as follows: 9.443(65)(001), 5.596(25)(011), 4.929(80)(210), 4.719(47)(002), 3.494(46)(400), 2.7958(100)(022). The crystal structure of whiteite-(CaMnMn) was refined for a single crystal twinned on (001) to R 1 = 0.068 on the basis of 5702 unique observed reflections. It is similar to the structures of other members of the whiteite group. The mineral is named for the chemical composition, in accordance with whiteite-group nomenclature.
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