Gregory Yu. Ivanyuk

3D mineralogical mapping of the Kovdor phoscorite–carbonatite complex (Russia)

The Kovdor baddeleyite–apatite–magnetite deposit in the Kovdor phoscorite–carbonatite pipe is situated in the western part of the zoned alkali-ultrabasic Kovdor intrusion (NW part of the Fennoscandinavian shield; Murmansk Region, Russia). We describe major intrusive and metasomatic rocks of the pipe and its surroundings using a new classification of phoscorite–carbonatite series rocks, consistent with the IUGS recommendation. The gradual zonation of the pipe corresponds to the sequence of mineral crystallization (forsterite–hydroxylapatite–magnetite–calcite). Crystal morphology, grain size, characteristic inclusions, and composition of the rock-forming and accessory minerals display the same spatial zonation pattern, as do the three minerals of economic interest, i.e. magnetite, hydroxylapatite, and baddeleyite. The content of Sr, rare earth elements (REEs), and Ba in hydroxylapatite tends to increase gradually at the expense of Si, Fe, and Mg from early apatite–forsterite phoscorite (margins of the pipe) through carbonate-free, magnetite-rich phoscorite to carbonate-rich phoscorite and phoscorite-related carbonatite (inner part). Magnetite displays a trend of increasing V and Ca and decreasing Ti, Mn, Si, Cr, Sc, and Zn from the margins to the central part of the pipe; its grain size initially increases from the wall rocks to the inner part and then decreases towards the central part; characteristic inclusions in magnetite are geikielite within the marginal zone of the phoscorite–carbonatite pipe, spinel within the intermediate zone, and ilmenite within the inner zone. The zoning pattern seems to have formed due to both cooling and rapid degassing (pressure drop) of a fluid-rich magmatic column and subsequent pneumatolytic and hydrothermal processes.

Chivruaiite, Ca4(Ti,Nb)5[(Si6O17)2[(OH,O)5]·13-14H2O, a new mineral from hydrothermal veins of Khibiny and Lovozero alkaline massifs

Abstract Chivruaiite is a new Ca titanosilicate [orthorhombic, Cmmm, a = 7.17(2), b = 22.98(9), c = 6.94(2) Å, V = 1144.4 Å3, Z = 1], chemically and structurally related to zorite. The mineral is found in three different hydrothermal veins within the Khibiny and Lovozero alkaline massifs, Kola Peninsula, Russia. It is associated with microcline, eudialyte, natrolite, astrophyllite, aegirine, etc. Chivruaiite occurs as elongate-prismatic crystals (up to 3 mm long) with {100}, {010}, {001}, {101}, and {011} as dominant faces, as well as radiating aggregates. The mineral is transparent, pale-pink to colorless, with vitreous luster and white streak. Cleavage is distinct on {100} and {010}; fracture is step-like. Mohs hardness is about 3. In transmitted light, the mineral is pale-pink, with a faint pleochroism: Z = pale-pink, on X and Y = colorless; dispersion r < v. Chivruaiite is biaxial (+): α =1.705(5), β = 1.627(2), γ = 1.612(2) (for λ = 589 nm), 2Vmeas = 40 ± 5°, 2Vcalc = 31.7°. Optical orientation: X = b, Y = a, Z = c, Dcalc = 2.42 g/cm3, Dmeas = 2.40.2.42 g/cm3. The mean chemical composition determined by electron microprobe is (wt%): SiO2 45.14; TiO2 20.63; Al2O3 0.07; Fe2O3 0.18; MnO 0.02; MgO 0.01; CaO 10.53; Na2O 0.10; K2O 1.30; SrO 0.28; Nb2O5 3.63; H2O 17.30; sum. 99.19. Empirical formula calculated on the basis of Si = 12 is (Ca3.00K0.44 Na0.05Sr0.04Mn0.01)Σ=3.54(Ti4.13Nb0.44Fe3+0.04 Al0.02)Σ=4.63[Si12O34 |(OH)4.51O0.49]·13.08H2O. Simplified formula is Ca4(Ti,Nb)5[(Si6O17)2|(OH,O)5]·13-14H2O. The strongest X-ray powder-diffraction lines [d in Å, (I), (hkl)] are 11.6 (100) (020), 6.91 (90) (110, 001), 5.23 (50) (130), 3.41 (50) (220), 3.35 (50) (061, 151), 3.04 (80) (221, 240). The structure of chivruaiite was refined to R1 = 0.038 on the basis of 687 unique observed reflections. It is based upon an open framework of SiO4 tetrahedra, TiO6 octahedra, and TiO5 pyramids. Framework cavities are occupied by Ca2+ and K+ cations, and H2O molecules. The mineral is named after its type locality in the Chivruai River valley (the Lovozero massif, Kola Peninsula, Russia). Chivruaiite is a Ca-analog of zorite and ETS-4 and is closely related to haineaultite.

Armbrusterite, K5Na6Mn3+Mn142+[Si9O22]4(OH)10·4H2O, a new Mn hydrous heterophyllosilicate from the Khibiny alkaline massif, Kola Peninsula, Russia

Abstract Armbrusterite, ideally K5Na6Mn3+Mn2+14[Si9O22]4(OH)10·4H2O, is a new silicate of potassium, sodium, and manganese found in a thin cancrinite-aegirine-microcline vein within urtite at Mt. Kukisvumchorr. The mineral occurs in intimate association with raite. Other associated minerals are lamprophyllite, mangan-neptunite, pectolite, vinogradovite, calcite, molybdenite, galena, sphalerite, and fluorite. Armbrusterite occurs as split, curved crystals and spherulites (≤2 mm diameter). The mineral is translucent (transparent in thin fragments), dark reddish-brown. It has vitreous luster and light-brown streak. Cleavage is perfect on (001) and the fracture is uneven. Mohs hardness is about 3.5. In transmitted light, the mineral is reddish-brown, with strong pleochroism: X = light yellowish-brown, Y and Z = dark reddish-brown; dispersion r > v, weak. Armbrusterite is biaxial (.): α = 1.532(2), β = 1.560(2), γ = 1.564(2) (for λ = 589 nm), 2V varies from 10° to 20°. Optical orientation: X is perpendicular to (001). The mean chemical composition determined by electron microprobe and the Penfield method (for H2O) is (wt%): Na2O 5.26, MgO 0.19, Al2O3 0.04, SiO2 56.02, K2O 6.13, CaO 0.26, TiO2 0.04, MnO 23.62, Mn2O3 2.07, FeO 0.65, ZnO 0.20, H2O 4.1, sum. 98.58. Empirical formula calculated on the basis of Si = 36 is K5.03Na6.55(Mn2+12.86Mn3+1.01Fe2+0.35Mg0.18 Ca0.18Zn0.09Al0.03Ti0.02)Σ=14.72[Si36O88](OH)10.10 ·3.75 H2O. Armbrusterite is monoclinic, C2/m, a = 17.333(2), b = 23.539(3), c = 13.4895(17) Å, β = 115.069(9)°, V = 4985.4(11) Å3, Z = 2. The strongest X-ray powder-diffraction lines are [d in Å, (I), (hkl)]: 12.28 (100) (001), 4.10 (10) (003), 3.562 (10) (113, 261), 3.260 (18) (114), 3.117 (13) (203), 3.077 (54) (004), 2.622 (10) (371). The crystal structure of armbrusterite was refined to R1 = 0.085 on the basis of 3960 unique observed reflections. The structure is based upon double silicate [Si9O22] layers consisting of 5-, 6-, 7-, and 8-membered tetrahedra rings. The layers are linked via octahedral sheets formed by Na and Mn octahedra. The interior of the double silicate layers is occupied by K+ cations and H2O molecules. The mineral is named in honor of Thomas Armbruster (b. 1950; University of Berne) for his outstanding contribution to structural mineralogy and crystallography, especially to the study of Mn-rich minerals.

Polezhaevaite-(Ce), NaSrCeF6, a new mineral from the Khibiny massif (Kola Peninsula, Russia)

Abstract Polezhaevaite-(Ce) NaSrCeF6 is a new member of the gagarinite mineral group [hexagonal, P63/m, a = 6.207(7) Å, c = 3.801(9) Å, V = 126.8(2) Å3, Z = 1]. It is found in a natrolitized microcline-aegirinesodalite lens within apatite-rich urtite at Mt. Koashva (Khibiny massif, Kola Peninsula, Russia) in association with аegirine, albite, arfvedsonite, astrophyllite, burbankite, catapleiite, chlorbartonite, djerfisherite, elpasolite, fluorapatite, fluorite, galena, hydroxylapatite, ilmenite, lamprophyllite, lorenzenite, leucophanite, microcline, natrolite, nepheline, orickite, pectolite, pyrochlore, sodalite, sphalerite, strontiofluorite, tainiolite, titanite, vinogradovite, and villiaumite. Polezhaevaite-(Ce) occurs as parallel and sheaf-like aggregates of extremely thin fibers (up to 1 mm long and <1 μm thick), which fill leaching voids within burbankite crystals in natrolite and mantles around partially dissolved burbankite crystals in intimate association with strontiofluorite. Polezhaevaite-(Ce) is translucent (transparent in separate fibers), snowy-white, with a silky luster (in aggregates) and a white streak. Cleavage is not observed; fracture is splintery (in aggregates). The Mohs hardness of individual crystals could not be determined and approaches 3 in aggregates. In transmitted light, the mineral is colorless, uniaxial positive: ε = 1.497(5), ω = 1.490(5) (for λ = 589 nm). Dcalc = 4.646 g/cm3, Dmeas = >4.2 g/cm-3. The mean chemical composition determined by electron microprobe is (wt%): Na 5.27, Ca 3.08, Sr 29.72, Ba 0.48, La 11.76, Ce 14.12, Pr 0.49, Nd 3.09, F 31.95, total 99.96. Empirical formula calculated on the basis of F = 6 apfu is: (Na0.82Ca0.18)Σ=1.00(Sr1.21Ce0.36La0.30Ca0.09Nd0.08Ba0.01)Σ=2.06F6 (charge imbalance is +0.05). Its simplified formula is NaSrCeF6. The strongest X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 5.416(40)(100), 3.120(100)(101, 110), 2.198(70) (201), 1.796(90)(121, 211, 300, 102), 1.554(30)(220), 1.173(70)(321, 231, 140, 410,132, 312, 113). The mineral is named in honor of Lyudmila Ivanovna Polezhaeva (b. 1935), a Russian expert in electron microprobe analysis of minerals for her contribution to the mineralogy of alkaline rocks

First Natural Pharmacosiderite-Related Titanosilicates and Their Ion-Exchange Properties

In 1990, Chapman and Roe prepared a number of titanosilicate analogues of pharmacosiderite, including Cs, Rb and exchanged protonated phases. Harrison et al. (1995) reported structure of Cs3H[Ti4O4(SiO4)3](H2O)4. Behrens et al. (1996), Behrens and Clearfield (1997) and Dadachov and Harrison (1997) provided data on preparation, structures and properties of A 3H[Ti4O4(SiO4)3](H2O) n (A = H, Na, K, Cs). Structures and ion-exchanged properties of HA 3[M 4O4(XO4)3](H2O)4 (A = K, Rb, Cs; M = Ti, Ge; X = Si, Ge) were reported by Behrens et al. (1998). These compounds were considered as perspective materials for the selective removal of Cs and Sr from wastewater solutions. However, no natural titanosilicates with pharmacosiderite topology have been reported so far. In this article, we report for the first time occurrence of four pharmacosiderite-type titanosilicates in Nature and their cation-exchange properties.

Where Are New Minerals Hiding? The Main Features of Rare Mineral Localization Within Alkaline Massifs

Alkaline and alkaline-ultrabasic massifs of the Kola Peninsula are unrestrained world’s leaders in mineral diversity. More than 700 mineral species have been found here, and more than 200 of them – for the first time in the world. Discoveries of new minerals within alkaline massifs of the Kola Peninsula started in nineteenth century from W. Ramsay’s expeditions in the Khibiny and Lovozero mountains (Ramsay 1890; Ramsay and Hackman 1893) when lamprophyllite and murmanite were described. In twentieth century, quantity of minerals firstly discovered here was increasing exponentially with time, and well-known monograph of A. Khomyakov “Mineralogy of hyperagpaitic alkaline rock” (1995) gave list of 109 new minerals from these massifs. Now list of minerals discovered in the Khibiny and Lovozero massifs includes 198 species and constantly grows on 5–10 minerals per year.

Yakovenchukite-(Y),K3NaCaY2(Si12O30)(H2O)4, a new mineral from the Khibiny massif, Kola Peninsula, Russia: A novel type of octahedral-tetrahedral open-framework structure

Abstract Yakovenchukite-(Y), K3NaCaY2[Si12O30](H2O)4, is a new REE silicate found in a thin (3-4 cm) sodalite-aegirine-microcline veinlet cutting ijolite-urtite at Mt. Kukisvumchorr, Khibiny alkaline massif, Kola Peninsula, Russia. The mineral occurs as small prismatic crystals in intimate association with microcline, aegirine, calcite, catapleiite, donnayite-(Y), Fluorapophyllite, Fluorite, galena, lead, litharge, molybdenite, natrolite-gonnardite, pyrochlore, rinkite, strontianite, and vuorijarvite-K. Yakovenchukite-(Y) is creamy to colorless, with vitreous luster. The streak is white. The mineral is transparent, non-fluorescent. The Mohs hardness is about 5. The mineral is brittle. Cleavage is perfect on {100}, distinct on {010}, fracture is stepped. Densities are 2.83 g/cm3 (measured by sink/float in heavy liquids) and 2.72 g/cm3 (calculated). Yakovenchukite-(Y) is biaxial (+): nα = 1.520(5), nβ = 1.525(5), nγ = 1.538(5) (589 nm), 2V(meas.) = 60 ± 5°, 2V(calc.) = 61.86°. The optical orientation is Y = c, X = a, Z = b, pleochroism is not observed. Chemical analysis by electron microprobe (wt%): Na2O 4.32, K2O 10.73, CaO 3.42, Y2O3 15.49, Ce2O3 0.10, Dy2O3 0.68, Er2O3 0.88, Tm2O3 0.18, Yb2O3 1.53, ThO2 0.62, SiO2 57.55, H2O (by the Penfield method) 4.70, total 100.20. The empirical formula (based on Si = 12 apfu) is (K2.85 Na0.15)Σ3.00 Na1.00 (Ca0.71 Na0.60)Σ1.31 (Y1.72 Yb0.10 Er0.06 Dy0.05 Th0.03 Ce0.01 Tm0.01 Ca0.05)Σ2.03 [Si12 O30.02]·3.27H2O. According to single-crystal X-ray study yakovenchukite-(Y) is orthorhombic, Pcca, a = 14.972(8), b = 14.137(7), c = 14.594(8) Å, V = 3089(3) Å3, Z = 4. The strongest lines of the X-ray powder diffraction pattern are [dbs(Å) (Iobs) (hkl)]: 7.00 (40) (020), 6.57 (60) (102), 4.20 (50) (222), 3.337 (100) (331), 3.248 (90) (024), 3.101 (40) (142), 3.014 (80) (422), 2.608 (40) (404). The crystal structure of yakovenchukite-(Y) belongs to a new structure type of minerals and inorganic compounds. It is based on microporous octahedral-tetrahedral framework of SiO4-tetrahedra and YO6-octahedra. Silicate tetrahedra share corners to form unprecedented [Si12O30] sheets consisting of 4-, 6-, and 14-membered rings. The sheets are parallel to (001) and are linked into 3D framework through YO6 octahedra. Ca2+, K+, and Na+ cations are located within the framework cavities. The octahedral- tetrahedral framework possess channels extended along the a axis. The channel dimensions are 4.9 × 6.2 Å, which means the free crystallographic diameter of 2.2 × 3.5 Å, that allows classifying yakovenchukite-(Y) as a microporous material. Yakovenchukite-(Y) is the latest low-temperature hydrothermal mineral, formed by alteration of earlier REE-rich minerals (pyrochlore, rinkite, etc.). The mineral is named in honor of Victor N. Yakovenchuk, a mineralogist at the Geological Institute of the Kola Science Centre of the Russian Academy of Sciences, for his outstanding contribution to the mineralogy of alkaline and alkaline-ultrabasic massifs

Kihlmanite-(Ce), Ce2TiO2[SiO4](HCO3)2(H2O), a new rare-earth mineral from the pegmatites of the Khibiny alkaline massif, Kola Peninsula, Russia

Abstract Kihlmanite-(Ce), Ce2TiO2[SiO4](HCO3)2(H2O), is a new rare-earth titanosilicate carbonate, closely related to tundrite-(Ce). It is triclinic, P1̄ , 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)°, V = 533(1) Å3, 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) Å3, 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), 2Vcalc = 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: Na2O 0.13, Al2O3 0.24, SiO2 9.91, CaO 1.50, TiO2 11.04, MnO 0.26, Fe2O3 0.05, Nb2O5 2.79, La2O3 12.95, Ce2O3 27.33, Pr2O3 2.45, Nd2O3 8.12, Sm2O3 1.67, Gd2O3 0.49 wt.%, with CO2 15.0 and H2O 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 (Ca0.16Na0.11Mn0.02)Σ0.29[(Ce0.98La0.47Pr0.09Nd0.29Sm0.06Gd0.02)Σ1.91(Ti0.82Nb0.12)Σ0.94O2 (Si0.97Al0.03)Σ1O4.02(HCO3)2.01](H2O)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)(001̄), 7.508(20)(002̄), 6.912(12)(01̄1), 4.993(14)(003̄), 3.563(15)(02̄1), 2.896(15)(12̄2̄). The crystal structure of kihlmanite-(Ce) was refined to R1 = 0.069 on the basis of 2441 unique observed reflections (MoKα, 293 K). It is closely related to the crystal structure of tundrite-(Ce) and is based upon [Ce2TiO2(SiO4)(HCO3)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.

Ivanyukite-Group Minerals: Crystal Structure and Cation-Exchange Properties

Four microporous titanosilicates of the ivanyukite group: ivanyukite-Na-T, ivanyukite-Na-C, ivanyukite-K, and ivanyukite-Cu – were discovered in a natrolitized microcline-aegirine-sodalite vein within orthoclase-bearing urtite of the Koashva apatite deposit, Khibiny alklaine massif (Yakovenchuk et al. 2009). Ivanyukite-Na-T formed as a late-stage, hydrothermal phase resulting from alteration of lamprophyllite, whereas ivanyukite-Na-C, ivanyukite-K and ivanyukite-Cu are products of either cation exchange or hydration of ivanyukite-Na-T. It is noteworthy that crystals of ivanyukite-Cu were found in close association with corroded grains of djerfisherite and chalcopyrite (Ivanyuk et al. this book).

Eliseevite, Na1.5Li[Ti2Si4O12.5(OH)1.5]·2H2O, a new microporous titanosilicate from the Lovozero alkaline massif (Kola Peninsula, Russia)

Abstract 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.