Dear list members,
First of all happy new year !
I do not know if the following information will help you a lot but I give is to contribute to the debate...
These last years we studied a lot akaganeite, but only in corrosion products of archaeological ferrous artefacts. The investigation methods we used were : XRD, micro -XRD (on rotating anode X ray generator and under synchrotron radiation), µRaman spectrometry and XRay absorption (XAS).
A pHD (unfortunately in french) is published. You can download it at this address:
http://www-drecam.cea.fr/lps/TheseReguer/index.htm
You can find in it bibliographic review and particularly recent crystallographic data
Several paper are now published or in press
1. Reguer, S., et al., Local and structural characterisation of chlorinated phases formed on ferrous archaeological artefacts by µXRD and µXANES. Nuclear Instruments and Methods B, 2005. 240: p. 500-504.
2. Reguer, S., et al., Studies of the corrosion mechanisms related to the presence of chlorine on the archaeological ferrous artefacts. Contribution of the local and structural characterisation. Applied Physics A, 2006. 83: p. 189-193.
3. Réguer, S., et al., Deterioration of iron archaeological artefacts: µRaman investigation on chlorinated phases. Journal of Raman Spectroscopy, in press.
4. Réguer, S., P. Dillmann, and F. Mirambet, Buried iron archaeological artefacts: corrosion mechanisms related to the presence of Cl-containing phases. Corrosion Science, in press.
If you are interested, I can send you some PDF versions.
And important observation that we made, using these characterisation methods is that, in addition to akaganéite, another FeII phase was evidenced in corrosion products of numerous artefact : Fe2(OH)3Cl...
Unfortunately, I have no optical data on these phases. All I can say is that in black field under OM, Cl containing phases (but not only these phases) have a typical orange color.
Best regards
-----Message d'origine-----
De : Arch-Metals Group [mailto:[log in to unmask]] De la part de Ed
Envoyé : mardi 2 janvier 2007 22:04
À : [log in to unmask]
Objet : Re: Akaganeite
Hi,
I would add that XRD can be carried out on very small samples but it
requires the use of iron or cobalt radiation and a small diameter powder
camera (50 mm). Both of which in this hi-tech world are hard to locate.
Sincerely,
Ed Sharp
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=================================================
On Tue, 2 Jan 2007, David Scott wrote:
> Re the Akaganeite [sorry no accent over e in this system]
> problem....first of all I would say that identification by PLM might
> not be sufficient or easy....better to use XRD I would
> say....akaganeite is isostructural with hollandite which can have a
> tetragonal or monoclinic unit cell. Bernal [once thought to be the
> forth man in the famous spy scandal] thought it was tetragonal but
> recent work has shown it is more often monoclinic. Akaganeite has two
> basic morphologies according to Cornell and Schwertmann (2003: 75)
> somatoids and rods. Crystal lengths rarely greater than 0.5 microns.
> Crystals grown at room temperature may be square while those at higher
> temperatures are circular..HRTEM showed that crystals are homogeneous
> ...somatoids are often twinned to give star-shaped or x-shaped ...also
> possible confusion with schwertmannite in absence of XRD data...PLM
> data not specified anywhere as far as I can see. Probable confusion
> with other iron oxides possible in light microscope work. best wishes
> to all for 2007.....David A. Scott
>
> Quoting Donald B Wagner <[log in to unmask]>:
>
> > At 12:19 -0700 1/1/07, [log in to unmask] wrote:
> >> I was hoping that Vagn Buchwald might respond, since he has
> >> published on this
> >> mineral. The email address that I found for him on the web doesn't work - do
> >> you have a current one?
> >
> > Vagn refuses to have anything to do with the Internet - Write to him at
> > this address:
> >
> > Ingeborgvej 4
> > DK-2920 Charlottenlund
> > Denmark
> >
> > Regards
> > Don
> >
> > --
> > --------------------------------------------------------------------------------
> > dr.phil. Donald B. Wagner
> > Jernbanegade 9B
> > DK-3600 Frederikssund
> > Denmark
> > Tel. +45-3331 2581
> > http://alum.mit.edu/www/dwag
> > --------------------------------------------------------------------------------
>
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