Re: Uranium?

[Laurie Taylor <laurie-taylor@uiowa.edu>]

Al,
(I tried to e-mail you privately, but it won't go through).
My geology career is almost 20 years behind me, but I do remember that
micas can contain radioactive inclusions in them.  The recoil atoms can
produce circular colored zones around the inclusions in the mica that can
sometimes be observed (under microscope) due to the transparency of the
mineral.  Several black-brown rings may be observed, with the radii
corresponding to the range of the various alpha particles emitted by the
radioelement.  These rings are known as pleochroic halos, because when
exposed to light under a microscope they show different colors of light
depending on the orientation of the crystal.

Micas as sometime referred to as "garbage can"  minerals because (due to
their particular crystal lattice) they can accomodate a variety of
different elements.  It sounds like you may have some biotite mica?  I can
look through my old geology books and see if I can come up with a better
idea of the chemical formula of the mica that you have.  Do you have any
idea the type of rock that it is in?

Regards,
Laurie Taylor
Health Physics Associate
The University of Iowa
Health Protection Office
319-335-8532
laurie-taylor@uiowa.edu

At 12:48 PM 9/2/99 -0500, you wrote:
>All, 
>
>Some people  in the local community are renting a house where an old
chemist used to live and has since passed away. They were in the basement
and found some old books and writings talking about radioactivity. 
>To make a long story somewhat shorter, we went out and found that there
were what looked like uranyl acetate or nitrate crystals in one area of the
basement along with a rock that was found to be radioactive. Under a
dissecting scope, the rock had greenish yellow flecks embedded in it that
were easily removed with a needle. 
>Upon closer inspection of the crystals, they weren't really crystals at
all but had the same compisition of mica. They were yellow green and were
sheetlike, they would also crumble in your hand (I had gloves) under slight
to moderate pressure. I put them on our gamma spec and got a spectrum that
matched  the radium spectrum exactly. I know there is radium in uranium but
what kind of spectrum might I see? Could anyone give me an idea of what
this mineral (if it is) might be. 
>
>Replies can be sent to my private e-mail.
>
>Thanks in advance for your help.
>
>Al Castellane
>Oregon Health Sciences University
>castellla@ohsu.edu
>
>************************************************************************
>The RADSAFE Frequently Asked Questions list, archives and subscription
>information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
>
>
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html