Identification by RAMAN Microscopy of magnesian vivianite formed from Fe 2+ , Mg, Mn 2+ and P043-’ in a Roman camp near fort Vechten, Utrecht, The Netherlands
Abstract The presence of a magnesian vivianite (Fe 2+ ) 2.5 (Mg,Mn,Ca) 0.5 (PO 4 ) 2· 8H 2 O, has been identified in a soil sample from a Roman camp near Fort Vechten, The Netherlands, using a combination of Raman microscopy and scanning electron microscopy. An unsubstituted vivianite and baricite were characterised for comparative reasons. The split phosphate-stretching mode is recognised around 1115, 1062 and 1015 cm −1 , while the corresponding bending modes are found around 591, 519, 471 and 422 cm −1 . The substitution of Mg and Mn for Fe 2+ in the crystal structure causes a shift towards... Mehr ...
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Dokumenttyp: | Artikel |
Erscheinungsdatum: | 2003 |
Reihe/Periodikum: | Netherlands Journal of Geosciences ; volume 82, issue 2, page 209-214 ; ISSN 0016-7746 1573-9708 |
Verlag/Hrsg.: |
Cambridge University Press (CUP)
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Schlagwörter: | Geology |
Sprache: | Englisch |
Permalink: | https://search.fid-benelux.de/Record/base-27233369 |
Datenquelle: | BASE; Originalkatalog |
Powered By: | BASE |
Link(s) : | http://dx.doi.org/10.1017/s0016774600020758 |
Abstract The presence of a magnesian vivianite (Fe 2+ ) 2.5 (Mg,Mn,Ca) 0.5 (PO 4 ) 2· 8H 2 O, has been identified in a soil sample from a Roman camp near Fort Vechten, The Netherlands, using a combination of Raman microscopy and scanning electron microscopy. An unsubstituted vivianite and baricite were characterised for comparative reasons. The split phosphate-stretching mode is recognised around 1115, 1062 and 1015 cm −1 , while the corresponding bending modes are found around 591, 519, 471 and 422 cm −1 . The substitution of Mg and Mn for Fe 2+ in the crystal structure causes a shift towards higher wavenumbers compared to pure vivianite. As shown by the baričite sample substitution causes a broadening of the bands. The observed broadening however is larger than can be explained by substitution alone. The low intensity of the water bands, especially in the OH-stretching region between 2700 and 3700 cm −1 indicates that the magnesian vivianite is partially dehydrated, which explains the much larger broadening than the observed broadening caused by substitution of Mg and Mn in vivianite and baričite.