[NHCOLL-L:4146] Re: Cleaning oxidized pyrite mineral specimens

[Victoria Book]

I used a ~5% ammonium thioglycolate solution some years back to  
successfully remove rust stains from a limestone floor.  I haven't  
used it on specimens, but it makes sense that it would work (don't be  
alarmed when your clear solution suddenly looks like grape juice!).   
Ammonium thioglycolate is mercapt-acetic acid and ammonia brought to  
neutral pH--a mix of the two techniques mentioned in previous responses.

You probably already have it, but here is a reference for the  
ethanoamine thioglycollate for the rest of us: L. Cornish, A.M. Doyle.  
"Use of Ethanolamine Thioglycollate in the Conservation of Pyritised  
Fossils" Palaeontology 27(2), 1984, 421-424.

Who knows out Super Iron Out(r).  The problem with proprietary  
mixtures is that they are proprietary mixtures.  It is probably one or  
both of the above chemical mixed with surfactant.  I tend to avoid  
unknowns...

Victoria Book
Conservator
Sam Noble Oklahoma Museum of Natural History
University of Oklahoma
2401 Chautauqua Avenue
Norman, Oklahoma   73072-7029
phone 405.325.5163
fax 405.325.7699
www.snomnh.ou.edu



On Jan 8, 2009, at 6:53 PM, Robyn Hodgkins wrote:

> I am a UCLA chemistry graduate student helping the Natural History
> Museum of Los Angeles County Mineral Science department. They have
> several minerals containing iron sulfides that have become brown in
> color. The corrosion has not been completely identified, but we  
> believe
> it is mainly oxidized pyrite corrosion. The Museum is interested in
> cleaning these minerals. I have found literature about using
> ethanolamine thioglycollate to clean. Has anyone used this or has an
> opinion of how this would compare to Super Iron Out? thanks!
>
> Robyn Hodgkins
> Graduate Student
> Garrell Group
> UCLA Chemistry and Biochemistry
> hodgkins at chem.ucla.edu
> 310-206-9434
>

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