000028715 001__ 28715
000028715 005__ 20131002113959.0
000028715 0248_ $$aoai:doc.rero.ch:20120309093316-YH$$punifr$$ppostprint$$prero_explore$$zcdu34$$zthesis_urn$$zreport$$zthesis$$zbook$$zjournal$$zcdu549$$zcdu16$$zpreprint$$zcdu1$$zdissertation
000028715 041__ $$aeng
000028715 080__ $$a549
000028715 100__ $$aNagashima, Mariko$$uMineralogical Crystallography, Institute of Geological Sciences, University of Bern, Bern, Switzerland - Graduate School of Science and Engineering, Yamaguchi University, Japan
000028715 245__ $$9eng$$aSevere structural damage in Cr- and V-rich clinozoisite: relics of an epidote-group mineral with Ca₂ Al₂ Cr³⁺ Si₃ O₁₂ (OH) composition?
000028715 520__ $$9eng$$aCr-rich clinozoisite with up to 0.89 Cr³ apfu and additional 0.23 V³⁺ apfu originating from the Outokumpu copper mine, Finland, was studied by electron microprobe analyses, laser ablation inductively coupled-plasma mass spectrometry, single-crystal X-ray structure refinement of natural crystals and after step-wise annealing to a maximum temperature of 750°C, by HRTEM and electron backscattered diffraction. Although Cr-rich clinozoisite appears optically of gemmy quality with sharp extinction behavior under crossed polarizers, its X-ray and electron-diffraction behavior is very poor and resembles that of almost amorphous materials as known for strong metamictization. Albeit the sample does not contain significant U or Th as potential source of radiation and destruction of lattice periodicity. Cr- and V-free clinozoisite, intergrown with Cr- and V-rich clinozoisite, displays good diffraction behavior. Cr- and V-rich clinozoisite of poor diffraction quality has larger unit-cell volume than expected for its composition. The volume decreases with increasing annealing but does not reach the range expected for the analyzed composition. Heating cycles slightly improve crystallinity but the diffraction quality remains unsatisfactory. Site occupancy refinements of single-crystal X-ray data collected for natural crystals after heat treatment could not reproduce the (Cr + V) concentration previously determined by analytical methods. We speculate that probably on the retrograde path nano-particles of a Cr-(and V-) rich amorphous phase were exsolved destroying the periodicity of the residual clinozoisite. Annealing led to substantial structural cure but the original (Cr + V) content could not be reabsorbed.
000028715 695__ $$9eng$$aclinozoisite ; epidote ; chromium ; vanadium ; outokumpu ; amorphous ; metamict ; ''tawmawite''
000028715 700__ $$aArmbruster, Thomas$$uMineralogical Crystallography, Institute of Geological Sciences, University of Bern, Bern, Switzerland
000028715 700__ $$aHerwegh, Marco$$uInstitute of Geological Sciences, University of Bern, Switzerland
000028715 700__ $$aPettke, Thomas$$uInstitute of Geological Sciences, University of Bern, Switzerland
000028715 700__ $$aLahti, Seppo$$uGeological Survey of Finland, Espoo, Finland
000028715 700__ $$aGrobéty, Bernard$$uUniversity of Fribourg, Dep. of Geosciences and FRIMAT, Switzerland
000028715 773__ $$g2011/23/5/731-743$$tEuropean Journal of Mineralogy
000028715 775__ $$gPublished version$$ohttp://dx.doi.org/10.1127/0935-1221/2011/0023-2153
000028715 8564_ $$fgro_ssd.pdf$$qapplication/pdf$$s431536$$uhttp://doc.rero.ch/record/28715/files/gro_ssd.pdf$$yorder:1$$zpdf
000028715 918__ $$aFaculté des sciences$$bDécanat, Ch. du Musée 6A, 1700 Fribourg$$cGéosciences
000028715 919__ $$aUniversité de Fribourg$$bFribourg$$ddoc.support@rero.ch
000028715 980__ $$aPOSTPRINT$$bUNIFR$$fART_JOURNAL
000028715 990__ $$a20120309093316-YH