[Nhcoll-l] Blue/green discolouration of fossils or stoneartifacts

[Vicen Carrio Lluesma]

Hi Rhian,

I have some specimens in my collections, but mainly are sandstones. Apparently some moulds were done in the 70s with some pigments and never cleaned properly.
I tried some years ago to remove the colour without any luck.
Which kind of matrix have you got? Where from? Did the fossils had any kind of preparation?

Vicen

Ms Vicen Carrió
Geological Conservator/Preparator
Natural Sciences Department
National Museums Collection Centre
National Museums  Scotland
242 West Granton Road
Edinburgh EH5 1JA
tel +44(0)131 247 4254
email: v.carrio at nms.ac.uk
web:  www.nms.ac.uk/collectioncentre    
fax: +44(0)1312474322
 Note:  My working days are Monday to Thursday




-----Original Message-----
From: nhcoll-l-bounces at mailman.yale.edu [mailto:nhcoll-l-bounces at mailman.yale.edu] On Behalf Of Jabo, Steve
Sent: 11 October 2012 03:19
To: Rhian Russell; nhcoll-l at mailman.yale.edu
Subject: Re: [Nhcoll-l] Blue/green discolouration of fossils or stoneartifacts

The mineral vivianite can form secondarily on geologic specimens and cause them to look bluish. We have a mummified Pleistocene bison covered in it.

Steve

Steve Jabo
VP Prep Lab
Department of Paleobiology
Smithsonian Institution
P.O. Box 37012
Natural History, MRC-121
Washington, DC  20013-7012

jabos at si.edu
202.633.1332
202.786.2832 (fax)

________________________________________
From: nhcoll-l-bounces at mailman.yale.edu [nhcoll-l-bounces at mailman.yale.edu] On Behalf Of Rhian Russell [rhian.russell at gov.ab.ca]
Sent: Wednesday, October 10, 2012 5:38 PM
To: nhcoll-l at mailman.yale.edu
Subject: [Nhcoll-l] Blue/green discolouration of fossils or stone artifacts

Hello all,

We have encountered a phenomenon in our fossil collections where a few specimens have developed a blue/green discolouration, either on the surface of the fossil itself or in the surrounding rock. I've just read a paper describing the same thing happening to flints at the Natural History Museum in Verona (Tapparo et al., 2011, "The mystery of the discoloured flints. New molecules turn prehistoric lithic artifacts blue" in Journal of Analytical and Bioanalytical Chemistry Vol 399 (7) pp.2389 - 2393).

Basically, it seems that volatiles from certain plastics and/or rubbers react to cause the formation of a blue or green stain on the surface of the object and its surrounding matrix.

I'm wondering if anybody has seen this occur in other collections? It requires a very particular set of circumstances so I'm assuming it would be quite rare?

Cheers,

Rhian Russell
Conservation Technician
Royal Tyrrell Museum of Palaeontology,
Box 7500, Drumheller, Alberta T0J 0Y0
Phone: (403) 823 7707 Ext. 3306
E-mail: rhian.russell at gov.ab.ca<mailto:rhian.russell at gov.ab.ca>

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