Home 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
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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

  • Anthony R. Kampf EMAIL logo , Stuart J. Mills , William B. Simmons , James W. Nizamoff and Robert W. Whitmore
Published/Copyright: April 2, 2015
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American Mineralogist
From the journal American Mineralogist Volume 97 Issue 4

Abstract

Falsterite, ideally Ca2MgMn2+2(Fe20.5Fe3+0.5)4Zn4(PO4)8(OH)4(H2O)14, is a new mineral from the Palermo No. 1 pegmatite in North Groton, Grafton County, New Hampshire, U.S.A., and also occurs at the Estes pegmatite quarry, Baldwin, Cumberland County, Maine, U.S.A. It formed as the result of secondary alteration of primary triphylite and associated sphalerite. The crystals occur as very thin greenish-blue plates and rectangular laths, up to 0.7 mm in length, but no more than a few micrometers thick. Laths are flattened on {010}, elongate along [100], and exhibit lamellar twinning. The mineral is transparent and has a very pale greenish-blue streak, vitreous luster, Mohs hardness of about 2, flexible tenacity, irregular fracture, and perfect cleavage on {010}. The measured and calculated densities are 2.78(3) and 2.837 g/cm3, respectively. It is optically biaxial (-), a = 1.575(10), b = 1.600(5), g = 1.610(5) (white light), 2Vmeas = 60(10), and 2Vcalc = 63.8. Falsterite exhibits strong dispersion, r > v. The optical orientation is X = b, Y ≈ a, Z ≈ c. Pleochroism is pronounced: X, Z = colorless to very pale yellow, Y = blue green; Y >> X ≈ Z. Electron-microprobe analyses (average of 7), with FeO and Fe2O3 apportioned and H2O calculated on structural grounds, provided: CaO 6.36, MgO 2.13, MnO 8.10, ZnO 18.49, FeO 8.02, Fe2O3 8.90, Al2O3 0.02, P2O5 31.81, H2O 16.17, total 100.00 wt%. The empirical formula (based on 50 O atoms) is Ca2.02Mg0.94Mn2+2.04Fe2+1.99Fe2+1.99Zn4.05P7.99O32(OH)4(H2O)14. The mineral dissolves very easily in cold, dilute HCl. Falsterite is monoclinic, P21/c, with the unit-cell parameters: a = 6.3868(18), b = 21.260(7), c = 15.365(5) Å, b = 90.564(6), V = 2086.2(1.1) Å3, and Z = 2. The eight strongest lines in the X-ray powder diffraction pattern are [dobs in Å(I)(hkl)]: 12.86(34)(011); 10.675(100)(020); 4.834(12)(102,112); 4.043(18)(132); 3.220(25)(152); 3.107(14)(044); 2.846(19)(222); 1.596(14)(0·12·4). The structure of falsterite (R1 = 6.42% for 714 Fo > 4σF) contains edge-sharing chains of Fe2+/Fe3+O6 octahedra and corner-sharing chains of ZnO4 tetrahedra along [100]. These chains are linked to one another by PO4 tetrahedra, forming a sheet parallel to {010}. Mn2+O6 octahedra and CaO7 polyhedra also link to this sheet, resulting in a thick slab. The slabs are bridged in the [010] direction by edge-sharing dimers of MgO6 octahedra, which link to the slabs by sharing edges with ZnO4 tetrahedra in adjacent slabs. The structures of falsterite and schoonerite, while topologically quite different, share similar components and structural features.

Keywords: Falsterite; new mineral; crystal structure; schoonerite; secondary phosphate; Palermo No. 1 pegmatite; New Hampshire; U.S.A.
Received: 2011-9-20
Accepted: 2011-12-31
Published Online: 2015-4-2
Published in Print: 2012-4-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. Veatchite: Structural relationships of the three polytypes
  2. 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
  3. 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
  4. Zaccagnaite-3R, a new Zn-Al hydrotalcite polytype from El Soplao cave (Cantabria, Spain)
  5. Incorporation of Si into TiO2 phases at high pressure
  6. TOF-SIMS and electron microprobe investigations of zoned magmatic orthopyroxenes: First results of trace and minor element analysis with implications for diffusion modeling
  7. Titanium in muscovite, biotite, and hornblende: Modeling, thermometry, and rutile activities of metapelites and amphibolites
  8. Polysaccharide-catalyzed nucleation and growth of disordered dolomite: A potential precursor of sedimentary dolomite
  9. High-pressure and high-temperature phase transitions in FeTiO3 and a new dense FeTi3O7 structure
  10. Compressibility and thermal expansion of hydrous ringwoodite with 2.5(3) wt% H2O
  11. Vibrational and elastic properties of ferromagnesite across the electronic spin-pairing transition of iron
  12. Electronic spin states of ferric and ferrous iron in the lower-mantle silicate perovskite
  13. Experimental VNIR reflectance spectroscopy of gypsum dehydration: Investigating the gypsum to bassanite transition
  14. Nature of rehydroxylation in dioctahedral 2:1 layer clay minerals
  15. Thermal behavior of afghanite, an ABABACAC member of the cancrinite group
  16. Experimental incorporation of Th into xenotime at middle to lower crustal P-T utilizing alkali-bearing fluids
  17. Sol-gel synthesis of nanocrystalline fayalite (Fe2SiO4)
  18. The heat capacity of fayalite at high temperatures
  19. Structural trends for celestite (SrSO4), anglesite (PbSO4), and barite (BaSO4): Confirmation of expected variations within the SO4 groups
  20. The dehydroxylation of serpentine group minerals
  21. Formation of nanoscale Th-coffinite
  22. Magnetic and low-temperature structural behavior of clinopyroxene-type FeGeO3: A neutron diffraction, magnetic susceptibility, and 57Fe Mössbauer study
  23. Crystal structure and thermal expansion of aragonite-group carbonates by single-crystal X-ray diffraction
  24. The lower-pressure stability of glaucophane in the presence of paragonite and quartz in the system Na2O-MgO-Al2O3-SiO2-H2O
  25. 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
  26. The crystal structure of metanatroautunite, Na[(UO2)(PO4)](H2O)3, from the Lake Boga Granite, Victoria, Australia
  27. Petedunnite (CaZnSi2O6): Stability and phase relations in the system CaO-ZnO-SiO2
  28. Revision of the crystal structure and chemical formula of weeksite, K2(UO2)2(Si5O13)·4H2O
  29. Electron backscatter diffraction (EBSD) analyses of phyllosilicates in petrographic thin sections
https://doi.org/10.2138/am.2012.4008
Keywords for this article
Falsterite; new mineral; crystal structure; schoonerite; secondary phosphate; Palermo No. 1 pegmatite; New Hampshire; U.S.A.

Articles in the same Issue

  1. Veatchite: Structural relationships of the three polytypes
  2. 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
  3. 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
  4. Zaccagnaite-3R, a new Zn-Al hydrotalcite polytype from El Soplao cave (Cantabria, Spain)
  5. Incorporation of Si into TiO2 phases at high pressure
  6. TOF-SIMS and electron microprobe investigations of zoned magmatic orthopyroxenes: First results of trace and minor element analysis with implications for diffusion modeling
  7. Titanium in muscovite, biotite, and hornblende: Modeling, thermometry, and rutile activities of metapelites and amphibolites
  8. Polysaccharide-catalyzed nucleation and growth of disordered dolomite: A potential precursor of sedimentary dolomite
  9. High-pressure and high-temperature phase transitions in FeTiO3 and a new dense FeTi3O7 structure
  10. Compressibility and thermal expansion of hydrous ringwoodite with 2.5(3) wt% H2O
  11. Vibrational and elastic properties of ferromagnesite across the electronic spin-pairing transition of iron
  12. Electronic spin states of ferric and ferrous iron in the lower-mantle silicate perovskite
  13. Experimental VNIR reflectance spectroscopy of gypsum dehydration: Investigating the gypsum to bassanite transition
  14. Nature of rehydroxylation in dioctahedral 2:1 layer clay minerals
  15. Thermal behavior of afghanite, an ABABACAC member of the cancrinite group
  16. Experimental incorporation of Th into xenotime at middle to lower crustal P-T utilizing alkali-bearing fluids
  17. Sol-gel synthesis of nanocrystalline fayalite (Fe2SiO4)
  18. The heat capacity of fayalite at high temperatures
  19. Structural trends for celestite (SrSO4), anglesite (PbSO4), and barite (BaSO4): Confirmation of expected variations within the SO4 groups
  20. The dehydroxylation of serpentine group minerals
  21. Formation of nanoscale Th-coffinite
  22. Magnetic and low-temperature structural behavior of clinopyroxene-type FeGeO3: A neutron diffraction, magnetic susceptibility, and 57Fe Mössbauer study
  23. Crystal structure and thermal expansion of aragonite-group carbonates by single-crystal X-ray diffraction
  24. The lower-pressure stability of glaucophane in the presence of paragonite and quartz in the system Na2O-MgO-Al2O3-SiO2-H2O
  25. 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
  26. The crystal structure of metanatroautunite, Na[(UO2)(PO4)](H2O)3, from the Lake Boga Granite, Victoria, Australia
  27. Petedunnite (CaZnSi2O6): Stability and phase relations in the system CaO-ZnO-SiO2
  28. Revision of the crystal structure and chemical formula of weeksite, K2(UO2)2(Si5O13)·4H2O
  29. Electron backscatter diffraction (EBSD) analyses of phyllosilicates in petrographic thin sections
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