[ RadSafe ] Uranium Source

A Karam paksbi at rit.edu
Thu Jun 22 09:49:21 CDT 2006

It's not uncommon to find U minerals that have formed in fossilized plants.  Among the hottest natural rocks I've handled was a large piece of fossilized wood (petrified wood) - it was literally a chunk of wood in which much of the organic material had been replaced by uranium minerals.  I have to admit I did not do any extensive testing, but it felt about as dense as many lead minerals we played with in geology labs and measured about 400 mr/hr beta dose and over 100 mr/hr gamma at a distance of 1 cm or so.  What was neat is that you could still see the texture of the wood.
What happens is that U is soluble in oxygen-rich surface waters and is insoluble in anoxic waters.  So what can happen is that you have a tree fall in a swampy environment and the branch ends up in the anoxic muck at the bottom (or tree roots can do this too).  Then, over time, uraniferous surface waters enter the swamp and mix into the anoxic bottom waters where the U precipitates out and - if you're lucky - replaces some of the organic molecules in the wood.  Neat stuff! 
P. Andrew Karam, Ph.D., CHP
Senior Health Physicist
MJW Corporation
pkaram at oraucoc.org
People who believe they are ignorant of nothing have neither looked for, nor stumbled upon, the boundary between what is known and unknown....  Neil deGrasse Tyson, Director, Hayden Planetarium in "In the Beginning", Natural History Magazine, Sept 2003


From: radsafe-bounces at radlab.nl on behalf of Mercado, Don
Sent: Thu 6/22/2006 10:42
To: radsafe at radlab.nl
Subject: [ RadSafe ] Uranium Source

Greetings all,

I was in the Petrified Forest in Calistoga, CA last weekend and went to
their tourist shop. They sell all kinds of minerals, pieces of petrified
trees, geodes, fossils, etc. A display box on the counter right near the
check out clerk had about 50 one cubic inch clear plastic boxes labeled
"Uranium" with a half-dime sized chunk of yellow and grey flaky rock in
it. For $3.00 I had to have one. I got it to my lab yesterday (no, I
didn't transport it in accordance with DOT regulations!! :^)  ) and it
is running about 30,000 cpm on a thin window GM at the surface of the
box, more with the box open. I'm going to run it through my spectrum
analyzer just to see what's there. I'd like to go back there with an ion
chamber and see what those high school aged clerks are being exposed to.

I also went to the Old Faithful Geyser they have in Calistoga. Didn't
take any radon samples....

Donald P. Mercado
Radiation Safety Officer
Explosives Safety Officer
Lockheed Martin Space Systems Company
O/9K-2S, B/157
1111 Lockheed Martin Way
Sunnyvale, CA 94089
Ph. (408) 742-0759
Fx. (408) 756-0504
Don.Mercado at lmco.com
"Life is not a journey to the grave with the intention of
arriving safely in a pretty and well preserved body, but
rather to skid in broadside, thoroughly used up, totally
worn out, and loudly proclaiming
-- WOW!!! -- What a Ride!!!"

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