Davidite from South Australia

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Go-Figure
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Davidite from South Australia

Post by Go-Figure » 09 Mar 2020, 07:33

Hello there,
Today I am reporting on a test I’ve done last week on a sample of Davidite from South Australia. The sample weight is roughly 160 grams and as you can see it’s really beautiful.
01 - DSC07793R.jpg
02 - DSC07796R.jpg
My Ranger got some 17000-17500 CPM from it which is not that impressive compared with other Uranium ores I tested. By contrast the gamma activity was pretty high, from a 2000 seconds MCA data acquisition with my PDS I got an average of 1432 CPS and a dose at contact of 4.42 µSv/h.
Another thing I noticed was that putting the sample into the plastic bag the read on the Geiger counter was still about 16000-16500 CPM. The difference between the read with and without plastic bag is generally alpha radiation which therefore is lower than expected in this case. It could be a matter of geometry given that the sample is bigger than the average uranium ore I usually test, so maybe a lower percentage of alphas made it to the pancake probe.
03 - DSC07822R.jpg
04 - DSC07826R.jpg
05 - DSC07839R.jpg
The PDS spectrum gave me all the expected peaks from Uranium albeit the X-Rays peak from Pb214 is usually more prominent in terms of counts compared with the others. Here the “fingers” of Uranium have all a similar number of counts.
I usually get 4-5 times more counts from the 2’’x2’’ NaI(Tl) than from the PDS which made likely that the sample was going to saturate my sound card capacity.
06 - Davidite - 2000 secs - 29-02-20 - LIN.png
07 - Davidite - 2000 secs - 29-02-20 - LOG.png
For this measurement I didn’t use any shielding, the sample was hot enough that a simple background subtraction sufficed. Doing so I was sure to get rid of any chance, however small, of fluorescence making its way in the final spectrum.

So here’s the final spectrum, both in counts per bin and energy per bin.
08 - Davidite - ID - 4 Hours - BG Subtraction - Counts x Bin - No Shield - 0.045 Clean - 29-02-20.png
09 - Davidite - ID - 4 Hours - BG Subtraction - Energy x Bin - No Shield - 0.045 Clean - 29-02-20.png
No real surprise. The spectrum confirms that the Pb214 X-Rays peak is less prominent than usual. You can see that there appears to be something else close to it. It looks like a Th234 peak at 92 keV, but I didn’t put a label there because when you see the 92 keV peak from Th234 you would expect to see the 63 keV peak as well and there’s no sign of it, not even a gaussian correlation.

As mentioned above I expected the sample to saturate my sound card capacity so I didn’t try too hard to find the best possible geometry to maximise counts. Therefore the quantitative analysis is not very much significant for this one.
10 - Spectrum Analysis-001.jpg
In summary, nice sample, expected peaks but still a thing or two to scratch your head on and even something left unresolved. So, even if it’s just another Uranium ore there’s always something to learn.

Until next time.

Massimo

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Geoff
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Re: Davidite from South Australia

Post by Geoff » 09 Mar 2020, 12:01

Very nice article and specimen.
Geoff Van Horn

Former Alaskan living in rural Wisconsin

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pilgrim
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Re: Davidite from South Australia

Post by pilgrim » 11 Mar 2020, 06:25

Hi Massimo, as usual very nice report.
The sample is very beautiful, I didn't even know Davidite existed!
Daniel, Italy

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elemental
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Location: Willunga South, South Australia
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Re: Davidite from South Australia

Post by elemental » 11 Mar 2020, 07:07

Where from in south Australia?

Crocker’s well or radium hill?

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Go-Figure
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Re: Davidite from South Australia

Post by Go-Figure » 13 Mar 2020, 00:30

Thanks guys.
elemental wrote:
11 Mar 2020, 07:07
Where from in south Australia?

Crocker’s well or radium hill?
The little card inside the package says "West Crockers Well".
The sample is very beautiful, I didn't even know Davidite existed!
It was a self present for Christmas. You know, bad kids get coal, good kids get Uranium!

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pilgrim
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Re: Davidite from South Australia

Post by pilgrim » 14 Mar 2020, 07:02

Go-Figure wrote:
13 Mar 2020, 00:30
You know, bad kids get coal, good kids get Uranium!
This sentence was great : I'll make it mine!! :-) :-) :-)
Daniel, Italy

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