[NHCOLL-L:4159] RE: Cleaning oxidized pyrite mineral specimens

[Del Re, Christine]

I agree with Cathy Hawks and Greg and would further refer you to an
article written by Julia Day for the ICOM-Conservation Committee Mtgs,
Netherlands 2005 (I do not have the complete reference at my fingertips
right now) which describes in detail how to create the appropriate
microclimate needed for long-term preservation of such specimens.  

 

Chris Del Re, Milwaukee Public Museum

From: owner-nhcoll-l at lists.yale.edu
[mailto:owner-nhcoll-l at lists.yale.edu] On Behalf Of CAHawks at aol.com
Sent: Wednesday, January 14, 2009 8:53 AM
To: gbrown1 at unl.edu; hodgkins at chem.ucla.edu; NHCOLL-L at lists.yale.edu
Subject: [NHCOLL-L:4158] RE: Cleaning oxidized pyrite mineral specimens

 

I agree with Greg. Doesn't matter what treatment you apply, the only
sure way to protect a specimen that has been decreptitating is to keep
it below 30% RH. At that level, the oxidation becomes metastable.

 

Cathy

 

Catharine Hawks
Conservator
2419 Barbour Road
Falls Church VA 22043-3026 USA
t/f 703.876.9272
mobile 703.200.4370 

 

In a message dated 1/14/2009 9:41:58 A.M. Eastern Standard Time,
gbrown1 at unl.edu writes:

	Robyn,
	
	I hesitate to contribute to this thread since you have already
heard from some of the best minds in
	geological conservation and I'm merely a vertebrate paleo
preparator, but...
	
	Two things you might want to keep in mind, one perhaps more
philosophical, one practical: 
	1) To borrow loosly from Freud...sometimes a cigar is just a
cigar, or in the case of minerals, sometimes
	(depending upon mineral species) oxidation, although perhaps not
aesthetically pleasing, is a legitimate
	part of the mineral specimen. Removal in that case is neither
necessary nor wise since oxidation (again,
	depending upon mineral species) is not necessarily damaging and
treatment itself may be! (Obviously, if
	you are actually dealing with pyrite decay, this does not
apply.)
	
	2) If cleaning is warranted, it is only the first step.  All
treated specimens, at the very least, must
	be provided with a storage environment that effectively controls
RH levels to prevent a recurrence of the
	problem.  Contrary to some proprietary claims, there is no
effective treatment (sealant, consolidant or
	other goop) that can prevent pyrite oxidation in a specimen
stored in high RH.  Depending upon the
	specimen, you may even want to consider anoxic enclosures.
	
	I'd recommend consulting with a mineral conservator that can
look at your actual specimens and determine
	the best treatments.  Also recommended: The Care and
Conservation of Geological Material: Minerals,
	Rocks, Meteorites and Lunar Finds by Frank Howie(Butterworth -
Heinemann Series in Conservation and
	Museology) and the excellent three volume Science for
Conservators series published by the Museums and
	Galleries Commission.  These references are very helpful in
providing a non-conservator with the basic
	information they need to assess the value and appropriateness of
treatments they may be considering.
	
	Greg
	
	Gregory Brown
	Chief Preparator
	Vertebrate Paleontology
	University of Nebraska State Museum
	W-436 Nebraska Hall UNL
	Lincoln, NE 68588-0514
	402.472.2657
	GBROWN1 at UNL.EDU 
	
	
	
	
	> -----Original Message-----
	> From: Robyn Hodgkins [mailto:hodgkins at chem.ucla.edu] 
	> Sent: Friday, January 09, 2009 12:54 AM
	> To: NHCOLL-L at lists.yale.edu
	> Subject: [NHCOLL-L:4140] Cleaning oxidized pyrite mineral
specimens
	> 
	> 
	> 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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