RE: Radioactive Fossils

["Karam, Andrew" <Andrew_Karam@URMC.Rochester.edu>]

Dear Laurie -

I can't cite any specific sources regarding fossils.  However, U is pretty
soluble in oxidizing waters and insoluble in anoxic waters.  This is how,
for example, U ends up in coal and organic-rich shales.  The rotting
vegetation in a coal swamp removes the oxygen so that, when surface waters
bearing dissolved U mixes, the U precipitates out into the coal or organic
shale.  I would imagine that many fossils could come to rest in anoxic
waters, becoming uraniferous.  I have seen pyrite crystals on and in fossils
from similar mechanisms.  In addition, as mentioned by someone else, U can
replace Ca in shells and bones during the organism's life as well as after
its death.

Andy

P. Andrew Karam, CHP
Radiation Safety Officer
University of Rochester
(716) 275-1473 (voice)
(716) 256-0365 (fax)
andrew_karam@urmc.rochester.edu 

There is no Chase so pleasant, methinks, as to drive a Thought, by good
conduct, from one end of the World to the other; and never to lose sight
of it till it fall into Eternity, where all things are lost as to our
knowledge.    T. Burnet, The Theory of the Earth, 1697
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html