[NHCOLL-L:1485] Re: whale bone fossils fungus?

[Joy Irving]

Dear Angela,

The yellow powder sounds like pyrite decay caused by iron sulphide 
oxidation.  This often happens to certain vulnerable fossils and minerals 
that have been stored incorrectly, i.e., subjected to the daily highs and 
lows of humidity / temperature.  Does the yellow powder have a strong acidic 
/ sulphurous smell?  If you test it with pH paper, it will show up as pH 
1-3.

The good news is that it can be treated using ammonia gas to neutralize the 
acidity.  See the paper by Robert Waller (1987), An experimental ammonia gas 
treatment method for oxidized pyritic mineral specimens.  ICOM 8th triennial 
meeting preprints.  Sydney, 1987.  Or you could e-mail him at 
RWALLER at MUS-NATURE.CA.

After treatment and then consolidation of the specimens (preferably with 
Paraloid B.72 in acetone), it is really important to store them correctly, 
i.e., at a constant low RH (approx. 30-35%RH), where they will not be 
subjected to the daily fluctuations in humidity / temperature.  Since high 
humidity will re-start the whole process, store in well-sealed polyethylene 
boxes with correctly conditioned silica gel.

The 30-35%RH is a compromise, since bone material should be stored at about 
45-50%RH, but oxidation of iron sulphides in the presence of water vapour 
can happen, even at a low level, above 30%RH.  The important thing is that 
the specimens are stored in a constant, non-fluctuating RH.

I hope this is of some help!

                           Joy Irving
              Oxford University Museum of Natural History
                             U.K.


>From: "King, Angela" <AKing at spfldlibmus.org>
>Reply-To: AKing at spfldlibmus.org
>To: "NHCOLL LIST (E-mail)" <NHCOLL-L at lists.yale.edu>
>Subject: [NHCOLL-L:1482] whale bone fossils fungus?
>Date: Tue, 19 Feb 2002 15:13:33 -0500
>
>We have five small whale bone fossils (about 30,000,000 years old from Gay
>Head, Martha's Vineyard, Cape Cod, Mass. USA) that have a yellow dust like
>substance on them it is causing them to turn to dust. Humidity is 45%, 
>temp.
>is 68*F. Can fossil get fungus? Anyone know how to treat this safely?
>
>thanks,
>
>Angela C. King
>Collections Care Assistant
>Springfield Science Museum
>220 State Street
>Springfield, Mass. 01103
>U.S.A.
>(413)-263-6800 Ext. 397
>fax (413)-263-6884
>aking at spfldlibmus.org
>www.quadrangle.org
>
>






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