%0 Journal Article
%A Prieto Colorado, A.C.
%A Boiron, Marie Christine
%A Cathelineau, Michel
%A Mosser-Ruck, R.
%A López García, José Ángel
%A García, C.
%T Rythmic changes in crystal chemistry oftrioctahedral Cr-chlorites and Crentrapment: a SEM, EM and Raman study
%D 2003
%@ 0009-8558
%U https://hdl.handle.net/20.500.14352/58320
%X Back-scattered scanning electron microscopy (SEM) images of Cr-chlorite crystalsfrom Erzerum (Turkey) reveal that the crystals are chemically inhomogeneous and display complexbut well defined crystal zoning characterized by growth bands with contrasting chemical features.The chemical zoning has been investigated at the micron scale using an integrated approach,combining BSEM images, in situ chemical analysis by electron microprobe and Ramanspectroscopy. Enrichment in Cr, due to octahedral Al substitution, reaches up to 0.7 atoms perhalf formula, especially in bands where the Mg content is depleted. These substitutions are alsodepicted at the micron scale on Raman spectra by changes in the n(OH) band intensities andpositions that correlate with the Cr content. The Cr-enrichment occurs thus during specific stages ofcrystal growth, probably in response to changes in the fluid chemistry controlling the relativeavailability of Cr, Mg and Al in solution.
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