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Witzkeite: A new rare nitrate-sulphate mineral from a guano deposit at Punta de Lobos, Chile

  • Fabrizio Nestola EMAIL logo , Fernando Cámara , Nikita V. Chukanov , Daniel Atencio , José M.V. Coutinho , Reynaldo R. Contreira Filho and Gunnar Färber
Published/Copyright: April 2, 2015
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American Mineralogist
From the journal American Mineralogist Volume 97 Issue 10

Abstract

Witzkeite, ideally Na4K4Ca(NO3)2(SO4)4·2H2O, is a new mineral found in the oxidation zone of the guano mining field at Punta de Lobos, Tarapacá region, Chile. It occurs as colorless, tabular crystals up to 140 μm in length, associated with dittmanite and nitratine. Witzkeite is colorless and transparent, with a white streak and a vitreous luster. It is brittle, with Mohs hardness 2 and distinct cleavage on {001}. Measured density is 2.40(2) g/cm3, calculated density is 2.403 g/cm3. Witzkeite is biaxial (-) with refractive indexes α = 1.470(5), β = 1.495(5), γ = 1.510(5), measured 2V = 50-70°. The empirical composition is (electron microprobe, mean of five analyses, H2O, CO2, and N2O5 by gas chromatography; wt%): Na2O 12.83, K2O 22.64, CaO 7.57, FeO 0.44, SO3 39.96, N2O5 12.7, H2O 4.5, total 100.64; CO2 was not detected. The chemical formula, calculated based on 24 O, is: Na3.40K3.95Ca1.11Fe0.05(NO3)1.93(SO4)4.10(H4.10O1.81). Witzkeite is monoclinic, space group C2/c, with unit-cell parameters: a = 24.902(2), b = 5.3323(4), c = 17.246(1) Å, β = 94.281(7)°, V = 2283.6(3) Å3 (Z = 4). The crystal structure was solved using single-crystal X-ray diffraction data and refined to R1(F) = 0.043. Witzkeite belongs to a new structure type and is noteworthy for the very rare simultaneous presence of sulfate and nitrate groups. The eight strongest X-ray powder-diffraction lines [d in Å (I in %) (h k l)] are: 12.38 (100) (2 0 0), 4.13 (19) (6 0 0), 3.10 (24) (8 0 0), 2.99 (7) (8̄ 0 2), 2.85 (6) (8 0 2), 2.69 (9) (7̅ 1 3), 2.48 (12) (10 0 0), and 2.07 (54) (12 0 0). The IR spectrum of witzkeite was collected in the range 390-4000 cm-1. The spectrum shows the typical bands of SO42- ions (1192, 1154, 1116, 1101, 1084, 993, 634, and 617 cm-1) and of NO3- ions (1385, 1354, 830, 716, and 2775 cm-1). Moreover, a complex pattern of bands related to H2O is visible (bands at 3565, 3419, 3260, 2405, 2110, 1638, and 499 cm-1). The IR spectrum is discussed in detail.

Keywords : Witzkeite; new mineral; guano; crystal structure; sulfate; nitrate; IR spectroscopy
Received: 2012-1-16
Accepted: 2012-6-5
Published Online: 2015-4-2
Published in Print: 2012-10-1

© 2015 by Walter de Gruyter Berlin/Boston

Articles in the same Issue

  1. MSA Roebling medal lecture. Mineralogy, petrology, U-Pb geochronology, and geologic evolution of the Dabie-Sulu classic ultrahigh-pressure metamorphic terrane, East-Central China
  2. Brittle-ductile microfabrics in naturally deformed zircon: Deformation mechanisms and consequences for U-Pb dating
  3. In situ hot-stage AFM study of the dissolution of the barite (001) surface in water at 30–55 °C
  4. A multi-domain gem-grade Brazilian apatite
  5. High-temperature structural behaviors of anhydrous wadsleyite and forsterite
  6. Rates and mechanism of Y, REE, and Cr diffusion in garnet
  7. EPR discrimination of microcrystalline calcite geomaterials
  8. Crystal chemistry of Bi- and Mn-bearing vesuvianite from Långban, Sweden
  9. Cation ordering in Pb2+-bearing, Mn3+-rich pargasite from Långban, Sweden
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  11. The sulfur speciation in S-bearing minerals: New constraints by a combination of electron microprobe analysis and DFT calculations with special reference to sodalite-group minerals
  12. Simultaneous sound velocity and density measurements of NaCl at high temperatures and pressures: Application as a primary pressure standard
  13. The temperature and compositional dependence of disordering in Fe-bearing dolomites
  14. Quantifying crystallization and devitrification of rhyolites by means of X-ray diffraction and electron microprobe analysis
  15. Reactions of strontium anorthite with H2O+CaCl2 fluids at 500 °C and high pressure: Kinetic information from in situ synchrotron-radiation XRF analyses of the fluid
  16. Solubility of xenotime in a 2 M HCl aqueous fluid from 1.2 to 2.6 GPa and 300 to 500 °C
  17. Elastic and anelastic anomalies due to spin-state transitions in orthorhombic perovskite from isoelectronic behavior of Co3+ and Fe2+
  18. Accurate determination of ferric iron in garnets by bulk Mössbauer spectroscopy and synchrotron micro-XANES
  19. Re-investigation of the crystal structure of enstatite under high-pressure conditions
  20. Second-order P6̄c2-P31c transition and structural crystallography of the cyclosilicate benitoite, BaTiSi3O9, at high pressure
  21. High-pressure structural studies of eskolaite by means of single-crystal X-ray diffraction
  22. Almandine: Lattice and non-lattice heat capacity behavior and standard thermodynamic properties
  23. Witzkeite: A new rare nitrate-sulphate mineral from a guano deposit at Punta de Lobos, Chile
  24. Krasheninnikovite, KNa2CaMg(SO4)3F, a new mineral from the Tolbachik volcano, Kamchatka, Russia
  25. Crystal structure of pseudojohannite, with a revised formula, Cu3(OH)2[(UO2)4O4(SO4)2](H2O)12
  26. Letter. A natural photoelectrochemical cell for water splitting: Implications for early Earth and Mars
  27. Letter. In situ observation of the breakdown of magnetite (Fe3O4) to Fe4O5 and hematite at high pressures and temperatures
  28. Letter. The crystal structure of bartelkeite, with a revised chemical formula, PbFeGeVI(Ge2IVO7) (OH)2·H2O, isotypic with high-pressure P21/m lawsonite
https://doi.org/10.2138/am.2012.4109
Keywords for this article
Witzkeite; new mineral; guano; crystal structure; sulfate; nitrate; IR spectroscopy

Articles in the same Issue

  1. MSA Roebling medal lecture. Mineralogy, petrology, U-Pb geochronology, and geologic evolution of the Dabie-Sulu classic ultrahigh-pressure metamorphic terrane, East-Central China
  2. Brittle-ductile microfabrics in naturally deformed zircon: Deformation mechanisms and consequences for U-Pb dating
  3. In situ hot-stage AFM study of the dissolution of the barite (001) surface in water at 30–55 °C
  4. A multi-domain gem-grade Brazilian apatite
  5. High-temperature structural behaviors of anhydrous wadsleyite and forsterite
  6. Rates and mechanism of Y, REE, and Cr diffusion in garnet
  7. EPR discrimination of microcrystalline calcite geomaterials
  8. Crystal chemistry of Bi- and Mn-bearing vesuvianite from Långban, Sweden
  9. Cation ordering in Pb2+-bearing, Mn3+-rich pargasite from Långban, Sweden
  10. Long-term solid-phase fate of co-precipitated U(VI)-Fe(III) following biological iron reduction by Thermoanaerobacter
  11. The sulfur speciation in S-bearing minerals: New constraints by a combination of electron microprobe analysis and DFT calculations with special reference to sodalite-group minerals
  12. Simultaneous sound velocity and density measurements of NaCl at high temperatures and pressures: Application as a primary pressure standard
  13. The temperature and compositional dependence of disordering in Fe-bearing dolomites
  14. Quantifying crystallization and devitrification of rhyolites by means of X-ray diffraction and electron microprobe analysis
  15. Reactions of strontium anorthite with H2O+CaCl2 fluids at 500 °C and high pressure: Kinetic information from in situ synchrotron-radiation XRF analyses of the fluid
  16. Solubility of xenotime in a 2 M HCl aqueous fluid from 1.2 to 2.6 GPa and 300 to 500 °C
  17. Elastic and anelastic anomalies due to spin-state transitions in orthorhombic perovskite from isoelectronic behavior of Co3+ and Fe2+
  18. Accurate determination of ferric iron in garnets by bulk Mössbauer spectroscopy and synchrotron micro-XANES
  19. Re-investigation of the crystal structure of enstatite under high-pressure conditions
  20. Second-order P6̄c2-P31c transition and structural crystallography of the cyclosilicate benitoite, BaTiSi3O9, at high pressure
  21. High-pressure structural studies of eskolaite by means of single-crystal X-ray diffraction
  22. Almandine: Lattice and non-lattice heat capacity behavior and standard thermodynamic properties
  23. Witzkeite: A new rare nitrate-sulphate mineral from a guano deposit at Punta de Lobos, Chile
  24. Krasheninnikovite, KNa2CaMg(SO4)3F, a new mineral from the Tolbachik volcano, Kamchatka, Russia
  25. Crystal structure of pseudojohannite, with a revised formula, Cu3(OH)2[(UO2)4O4(SO4)2](H2O)12
  26. Letter. A natural photoelectrochemical cell for water splitting: Implications for early Earth and Mars
  27. Letter. In situ observation of the breakdown of magnetite (Fe3O4) to Fe4O5 and hematite at high pressures and temperatures
  28. Letter. The crystal structure of bartelkeite, with a revised chemical formula, PbFeGeVI(Ge2IVO7) (OH)2·H2O, isotypic with high-pressure P21/m lawsonite
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