Hydroxyl ordering in igneous apatite
-
R. Chris Tacker
Abstract
Apatites from several pegmatites and two alkaline igneous environments were analyzed by electron microprobe and by micro-FTIR spectroscopy in the region 3000.4000 cm-1. Hydrogen bonding between OH and adjacent halogens shifts the OH-stretching modes and proves sensitive to the ordering of anions and cations within the apatite structure. With few exceptions, the spectrum of the stretching vibration can be modeled as a combination of peaks observed in synthetic apatites.
Relative concentrations of OH populations can be determined from unpolarized spectra of oriented specimens. Analysis of populations of OH-Cl and OH-F pairs shows that OH-Cl pairs occur at a frequency greater than expected from a random sequence. This finding confirms earlier results that Cl incorporation into the hexagonal fluorapatite structure requires a hydroxyl nearest neighbor.
Additional component bands suggest cationic ordering into the Ca2 site. Comparison of random mixing models with spectroscopic data suggests that Mn preferentially orders with OH. Limited data for the Kola apatite suggest the same for Sr and REE, in accord with previous results on the influence of OH on REE uptake. The small change in bond valence sum produced by substitution of an OH may explain the pairing of OH and Sr, but not with Mn.
Activity of HAp in apatite is proportional to the area of the peak at 3575 cm.1. Activity calculated from mole fraction of HAp in the normalized microprobe analysis may overestimate the activity of water in associated exchange equilibria. Ordering of Cl-OH-F sequences produces potential complications for thermodynamic models.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- The origin of the color of pearls in iridescence from nano-composite structures of the nacre
- “Invisible„ gold revealed: Direct imaging of gold nanoparticles in a Carlin-type deposit
- Behavior of cation vacancy in kenotetrahedral Cr-spinels from Albanian eastern belt ophiolites
- Displacement and strain fields around a [100] dislocation in olivine measured to sub-angstrom accuracy
- Kiglapait mineralogy IV: The augite series
- Metasomatic formation of kosmochlor-bearing diopside in peridotite xenoliths from North Island, New Zealand
- Determination of standard thermodynamic properties of sulfides in the Ag-Au-S system by means of a solid-state galvanic cell
- Hydroxyl ordering in igneous apatite
- Accommodation of the carbonate ion in apatite: An FTIR and X-ray structure study of crystals synthesized at 2–4 GPa
- Mg/Si ratios of aqueous fluids coexisting with forsterite and enstatite based on the phase relations in the Mg2SiO4-SiO2-H2O system
- The activity of silica, water, and the equilibration of intermediate and silicic magmas
- The CO2–H2O system: IV. Empirical, isothermal equations for representing vapor-liquid equilibria at 110–350 °C, P ≤ 150 MPa
- Repercussions of size heterogeneity on the measurement of specific surface areas of colloidal minerals: Combination of macroscopic and microscopic analyses
- The crystal-structure of synthetic NaNa2Mg5Si8O21(OH)3, a triclinic C1̄ amphibole with a triple-cell and excess hydrogen
- High-pressure phase transitions in Ca0.2Sr0.8Al2Si2O8feldspar
- Phase transition of Ca-perovskite and stability of Al-bearing Mg-perovskite in the lower mantle
- Mineralogy and petrology of a mullite-bearing pseudotachylyte: Constraints on the temperature of coseismic frictional fusion
- New developments in two-feldspar thermometry
- Ordered distribution of Au and Ag in the crystal structure of muthmannite, AuAgTe2, a rare telluride from Sacarîmb, western Romania
- Polytypism of cookeite in low-grade metapelites of the Cameros Basin, Spain: Lack of correlation of well-ordered polytypes with pressure
- Evolution of mineral compositions during eclogitization of subducting basaltic crust
- Mass balance during retrogression of eclogite-facies minerals in the Rongcheng eclogite, eastern Sulu ultrahigh-pressure terrane, China
- Synthesis of REE and Y phosphates by Pb-free flux methods and their utilization as standards for electron microprobe analysis and in design of monazite chemical U-Th-Pb dating protocol
- The chemistry and crystal structure of okanoganite-(Y) and comparison with vicanite-(Ce)
- An automated system for phase identification and quantitative composition determination using the electron microprobe: Theory and applications
- Piston-cylinder calibration at 400 to 500 MPa: A comparison of using water solubility in albite melt and NaCl melting
- Letter. Comparative planetary mineralogy: V/(Cr + Al) systematics in chromite as an indicator of relative oxygen fugacity
- Letter. Porous titanosilicate nanorods in the structure of yuksporite, (Sr,Ba)2K4(Ca,Na)14(⃞,Mn,Fe) {(Ti,Nb)4(O,OH)4[Si6O17]2[Si2O7]3}(H2O,OH)n, resolved using synchrotron radiation
Articles in the same Issue
- The origin of the color of pearls in iridescence from nano-composite structures of the nacre
- “Invisible„ gold revealed: Direct imaging of gold nanoparticles in a Carlin-type deposit
- Behavior of cation vacancy in kenotetrahedral Cr-spinels from Albanian eastern belt ophiolites
- Displacement and strain fields around a [100] dislocation in olivine measured to sub-angstrom accuracy
- Kiglapait mineralogy IV: The augite series
- Metasomatic formation of kosmochlor-bearing diopside in peridotite xenoliths from North Island, New Zealand
- Determination of standard thermodynamic properties of sulfides in the Ag-Au-S system by means of a solid-state galvanic cell
- Hydroxyl ordering in igneous apatite
- Accommodation of the carbonate ion in apatite: An FTIR and X-ray structure study of crystals synthesized at 2–4 GPa
- Mg/Si ratios of aqueous fluids coexisting with forsterite and enstatite based on the phase relations in the Mg2SiO4-SiO2-H2O system
- The activity of silica, water, and the equilibration of intermediate and silicic magmas
- The CO2–H2O system: IV. Empirical, isothermal equations for representing vapor-liquid equilibria at 110–350 °C, P ≤ 150 MPa
- Repercussions of size heterogeneity on the measurement of specific surface areas of colloidal minerals: Combination of macroscopic and microscopic analyses
- The crystal-structure of synthetic NaNa2Mg5Si8O21(OH)3, a triclinic C1̄ amphibole with a triple-cell and excess hydrogen
- High-pressure phase transitions in Ca0.2Sr0.8Al2Si2O8feldspar
- Phase transition of Ca-perovskite and stability of Al-bearing Mg-perovskite in the lower mantle
- Mineralogy and petrology of a mullite-bearing pseudotachylyte: Constraints on the temperature of coseismic frictional fusion
- New developments in two-feldspar thermometry
- Ordered distribution of Au and Ag in the crystal structure of muthmannite, AuAgTe2, a rare telluride from Sacarîmb, western Romania
- Polytypism of cookeite in low-grade metapelites of the Cameros Basin, Spain: Lack of correlation of well-ordered polytypes with pressure
- Evolution of mineral compositions during eclogitization of subducting basaltic crust
- Mass balance during retrogression of eclogite-facies minerals in the Rongcheng eclogite, eastern Sulu ultrahigh-pressure terrane, China
- Synthesis of REE and Y phosphates by Pb-free flux methods and their utilization as standards for electron microprobe analysis and in design of monazite chemical U-Th-Pb dating protocol
- The chemistry and crystal structure of okanoganite-(Y) and comparison with vicanite-(Ce)
- An automated system for phase identification and quantitative composition determination using the electron microprobe: Theory and applications
- Piston-cylinder calibration at 400 to 500 MPa: A comparison of using water solubility in albite melt and NaCl melting
- Letter. Comparative planetary mineralogy: V/(Cr + Al) systematics in chromite as an indicator of relative oxygen fugacity
- Letter. Porous titanosilicate nanorods in the structure of yuksporite, (Sr,Ba)2K4(Ca,Na)14(⃞,Mn,Fe) {(Ti,Nb)4(O,OH)4[Si6O17]2[Si2O7]3}(H2O,OH)n, resolved using synchrotron radiation
