TY - JOUR
T1 - Chemical state of sulfur in natural and synthetic lazurite by S K-edge xanes and X-ray photoelectron spectroscopy
AU - Fleet, Michael E.
AU - Liu, Xiaoyang
AU - Harmer, Sarah L.
AU - Nesbitt, H. Wayne
PY - 2005/10/1
Y1 - 2005/10/1
N2 - Lazurite with a composition close to [Na6Ca2 Al6Si6O24(SO4,S)2] has been synthesized by employing CaS + CaSO4 redox in hydrothermal-pressure experiments and reduction with Re foil in piston-cylinder experiments. A royal blue lazurite formed by annealing at 1200°C and 0.5 GPa; it has an Al-rich framework (Al/Si between 1.1 and 1.2) and coexists with minor amounts of a colorless sodalite phase of S-poor, Si-excess composition. The sodalite phase of experiments without a reducing agent is haüyne. The chemical state of sulfur in the synthetic products and in lazurite from Afghanistan and Baffin Island, Nunavut, has been investigated by S K-edge X-ray absorption near-edge structure (XANES) spectroscopy and S 2p X-ray photoelectron spectroscopy (XPS). Sulfate is the dominant species of sulfur in all samples of lazurite studied, and there are significant but subordinate amounts of sulfide bound only to Na+ cations. In addition, there is minor sulfite in some piston-cylinder products and minor native sulfur in the minerals. Polysulfides are not present above minimum levels of detection. Natural lazurite differs markedly from its synthetic equivalent in chemical composition and S K-edge XANES and S 2p3/2 XPS spectra, but these differences appear to have little bearing on color development. In synthetic haüyne, the cage sulfur species is exclusively sulfate.
AB - Lazurite with a composition close to [Na6Ca2 Al6Si6O24(SO4,S)2] has been synthesized by employing CaS + CaSO4 redox in hydrothermal-pressure experiments and reduction with Re foil in piston-cylinder experiments. A royal blue lazurite formed by annealing at 1200°C and 0.5 GPa; it has an Al-rich framework (Al/Si between 1.1 and 1.2) and coexists with minor amounts of a colorless sodalite phase of S-poor, Si-excess composition. The sodalite phase of experiments without a reducing agent is haüyne. The chemical state of sulfur in the synthetic products and in lazurite from Afghanistan and Baffin Island, Nunavut, has been investigated by S K-edge X-ray absorption near-edge structure (XANES) spectroscopy and S 2p X-ray photoelectron spectroscopy (XPS). Sulfate is the dominant species of sulfur in all samples of lazurite studied, and there are significant but subordinate amounts of sulfide bound only to Na+ cations. In addition, there is minor sulfite in some piston-cylinder products and minor native sulfur in the minerals. Polysulfides are not present above minimum levels of detection. Natural lazurite differs markedly from its synthetic equivalent in chemical composition and S K-edge XANES and S 2p3/2 XPS spectra, but these differences appear to have little bearing on color development. In synthetic haüyne, the cage sulfur species is exclusively sulfate.
KW - Lazurite
KW - Synthesis
KW - X-ray absorption near-edge structure (XANES)
KW - X-ray photoelectron spectroscopy (XPS)
UR - http://www.scopus.com/inward/record.url?scp=32944474104&partnerID=8YFLogxK
U2 - 10.2113/gscanmin.43.5.1589
DO - 10.2113/gscanmin.43.5.1589
M3 - Article
AN - SCOPUS:32944474104
VL - 43
SP - 1589
EP - 1603
JO - Canadian Mineralogist
JF - Canadian Mineralogist
SN - 0008-4476
IS - 5
ER -