Pavlovskyite Ca8(SiO4)2(Si3O10): A new mineral of altered silicate-carbonate xenoliths from the two Russian type localities, Birkhin massif, Baikal Lake area and Upper Chegem caldera, North Caucasus
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Evgeny V. Galuskin
,
Frank Gfeller
Abstract
The new mineral pavlovskyite Ca8(SiO4)2(Si3O10) forms rims together with dellaite Ca6(Si2O7)(SiO4)(OH)2 around galuskinite Ca7(SiO4)3CO3 veins cutting calcio-olivine skarns in the Birkhin gabbro massif. In addition, skeletal pavlovskyite occurs in cuspidine zones of altered carbonate xenoliths in the ignimbrites of the Upper Chegem caldera (North Caucasus). The synthetic analog of pavlovskyite has been synthesized before and is known from cement-like materials. Isotypic to pavlovskyite is the synthetic germanate analog Ca8(GeO4)2(Ge3O10). The crystal structure of pavlovskyite, space group Pbcn, a = 5.0851(1), b = 11.4165(3), c = 28.6408(8) Å, V = 1662.71(7) Å3, Z = 4, has been refined from X-ray single-crystal data to R1 = 3.87%. The new colorless mineral has a Mohs hardness of 6-6.5, biaxial (-), α = 1.656(2), β = 1.658(2), γ = 1.660(2) (589 nm), 2V (meas) = 80(5)°, 2V (calc) = 89.9°, medium dispersion: r > v, optical orientation: X = b, Y = c, Z = a.
For comparison with pavlovskyite, the crystal structure of kilchoanite Ca6(SiO4)(Si3O10) from the Birkhin massif [space group I2cm, a = 11.4525(2), b = 5.0867(1), c = 21.996(3) Å, V = 1281.40(4) Å3, Z = 4] has been refined from single-crystal X-ray data to R1 = 2.00%.
Pavlovskyite represents a 1:1 member of a polysomatic series with calcio-olivine γ-Ca2SiO4 and kilchoanite Ca6(SiO4)(Si3O10) as end-member modules. The structure is characterized by strongly folded trisilicate units (Si3O10) interwoven with a framework of CaO6 and CaO8 polyhedra. Olivine-like slices with orthosilicate groups are interstratified with the characteristic trisilicate module of Ca4(Si3O10) composition. Although the optical properties of pavlovskyite and kilchoanite are similar, both minerals can be distinguished by chemical analyses (different Ca/Si ratio), X-ray diffraction, and Raman spectroscopy. The new mineral is named after V.E. Pavlovsky (1901-1982), an outstanding geologist in the area of Eastern Siberia, in particular of the Baikal region.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Veatchite: Structural relationships of the three polytypes
- Falsterite, Ca2MgMn2+2 (Fe2+0.5Fe3+0.5)4Zn4(PO4)8(OH)4(H2O)14, a new secondary phosphate mineral from the Palermo No. 1 pegmatite, North Groton, New Hampshire
- Pavlovskyite Ca8(SiO4)2(Si3O10): A new mineral of altered silicate-carbonate xenoliths from the two Russian type localities, Birkhin massif, Baikal Lake area and Upper Chegem caldera, North Caucasus
- Zaccagnaite-3R, a new Zn-Al hydrotalcite polytype from El Soplao cave (Cantabria, Spain)
- Incorporation of Si into TiO2 phases at high pressure
- TOF-SIMS and electron microprobe investigations of zoned magmatic orthopyroxenes: First results of trace and minor element analysis with implications for diffusion modeling
- Titanium in muscovite, biotite, and hornblende: Modeling, thermometry, and rutile activities of metapelites and amphibolites
- Polysaccharide-catalyzed nucleation and growth of disordered dolomite: A potential precursor of sedimentary dolomite
- High-pressure and high-temperature phase transitions in FeTiO3 and a new dense FeTi3O7 structure
- Compressibility and thermal expansion of hydrous ringwoodite with 2.5(3) wt% H2O
- Vibrational and elastic properties of ferromagnesite across the electronic spin-pairing transition of iron
- Electronic spin states of ferric and ferrous iron in the lower-mantle silicate perovskite
- Experimental VNIR reflectance spectroscopy of gypsum dehydration: Investigating the gypsum to bassanite transition
- Nature of rehydroxylation in dioctahedral 2:1 layer clay minerals
- Thermal behavior of afghanite, an ABABACAC member of the cancrinite group
- Experimental incorporation of Th into xenotime at middle to lower crustal P-T utilizing alkali-bearing fluids
- Sol-gel synthesis of nanocrystalline fayalite (Fe2SiO4)
- The heat capacity of fayalite at high temperatures
- Structural trends for celestite (SrSO4), anglesite (PbSO4), and barite (BaSO4): Confirmation of expected variations within the SO4 groups
- The dehydroxylation of serpentine group minerals
- Formation of nanoscale Th-coffinite
- Magnetic and low-temperature structural behavior of clinopyroxene-type FeGeO3: A neutron diffraction, magnetic susceptibility, and 57Fe Mössbauer study
- Crystal structure and thermal expansion of aragonite-group carbonates by single-crystal X-ray diffraction
- The lower-pressure stability of glaucophane in the presence of paragonite and quartz in the system Na2O-MgO-Al2O3-SiO2-H2O
- Coralloite, Mn2+Mn23+(AsO4)2(OH)2·4H2O, a new mixed valence Mn hydrate arsenate: Crystal structure and relationships with bermanite and whitmoreite mineral groups
- The crystal structure of metanatroautunite, Na[(UO2)(PO4)](H2O)3, from the Lake Boga Granite, Victoria, Australia
- Petedunnite (CaZnSi2O6): Stability and phase relations in the system CaO-ZnO-SiO2
- Revision of the crystal structure and chemical formula of weeksite, K2(UO2)2(Si5O13)·4H2O
- Electron backscatter diffraction (EBSD) analyses of phyllosilicates in petrographic thin sections
Articles in the same Issue
- Veatchite: Structural relationships of the three polytypes
- Falsterite, Ca2MgMn2+2 (Fe2+0.5Fe3+0.5)4Zn4(PO4)8(OH)4(H2O)14, a new secondary phosphate mineral from the Palermo No. 1 pegmatite, North Groton, New Hampshire
- Pavlovskyite Ca8(SiO4)2(Si3O10): A new mineral of altered silicate-carbonate xenoliths from the two Russian type localities, Birkhin massif, Baikal Lake area and Upper Chegem caldera, North Caucasus
- Zaccagnaite-3R, a new Zn-Al hydrotalcite polytype from El Soplao cave (Cantabria, Spain)
- Incorporation of Si into TiO2 phases at high pressure
- TOF-SIMS and electron microprobe investigations of zoned magmatic orthopyroxenes: First results of trace and minor element analysis with implications for diffusion modeling
- Titanium in muscovite, biotite, and hornblende: Modeling, thermometry, and rutile activities of metapelites and amphibolites
- Polysaccharide-catalyzed nucleation and growth of disordered dolomite: A potential precursor of sedimentary dolomite
- High-pressure and high-temperature phase transitions in FeTiO3 and a new dense FeTi3O7 structure
- Compressibility and thermal expansion of hydrous ringwoodite with 2.5(3) wt% H2O
- Vibrational and elastic properties of ferromagnesite across the electronic spin-pairing transition of iron
- Electronic spin states of ferric and ferrous iron in the lower-mantle silicate perovskite
- Experimental VNIR reflectance spectroscopy of gypsum dehydration: Investigating the gypsum to bassanite transition
- Nature of rehydroxylation in dioctahedral 2:1 layer clay minerals
- Thermal behavior of afghanite, an ABABACAC member of the cancrinite group
- Experimental incorporation of Th into xenotime at middle to lower crustal P-T utilizing alkali-bearing fluids
- Sol-gel synthesis of nanocrystalline fayalite (Fe2SiO4)
- The heat capacity of fayalite at high temperatures
- Structural trends for celestite (SrSO4), anglesite (PbSO4), and barite (BaSO4): Confirmation of expected variations within the SO4 groups
- The dehydroxylation of serpentine group minerals
- Formation of nanoscale Th-coffinite
- Magnetic and low-temperature structural behavior of clinopyroxene-type FeGeO3: A neutron diffraction, magnetic susceptibility, and 57Fe Mössbauer study
- Crystal structure and thermal expansion of aragonite-group carbonates by single-crystal X-ray diffraction
- The lower-pressure stability of glaucophane in the presence of paragonite and quartz in the system Na2O-MgO-Al2O3-SiO2-H2O
- Coralloite, Mn2+Mn23+(AsO4)2(OH)2·4H2O, a new mixed valence Mn hydrate arsenate: Crystal structure and relationships with bermanite and whitmoreite mineral groups
- The crystal structure of metanatroautunite, Na[(UO2)(PO4)](H2O)3, from the Lake Boga Granite, Victoria, Australia
- Petedunnite (CaZnSi2O6): Stability and phase relations in the system CaO-ZnO-SiO2
- Revision of the crystal structure and chemical formula of weeksite, K2(UO2)2(Si5O13)·4H2O
- Electron backscatter diffraction (EBSD) analyses of phyllosilicates in petrographic thin sections
