?

I’m really enjoying all of the discussion about analyzing various materials with XRF.? I’m quite impressed with the resolution and detail that some of you are obtaining using your ‘amateur’ in-home laboratories.??? I use the term “amateur” lightly – you put the efforts of my past experience in a chemistry laboratory at a nuclear power plant to shame.? Granted, our objective was to analyze for very specific elements of interest, primarily zinc and cobalt, and maybe iron and chromium as well.? We had our XRF set up in a very simplistic manner of push-button, get-banana.? We never strayed from any elements outside of an atomic number Z-range of 24 to 30.

?

Anyway, back to my main point of discussion.? I’ve always been a rockhound, and can’t resist picking up something of interest.? Last year I snagged a couple of pieces of some greenish-gray cobble stone that had some white veins of calcite running through it.? On a lark, when it got dark, I shined my Convoy S2+ UV-LED flashlight on the stone.? I wasn’t surprised to see some red fluorescence in the calcite, but was surprised by a relatively bright red phosphorescence that lasted for a few tenths of a second.? What I found even more perplexing is that this phenomenon only seemed to be evident when the stone was illuminated with the Convoy UV flashlight.? I tried getting fluorescence excitation with a combination longwave-shortwave Model UVSL-15 Mineralight (longwave 365 nm, shortwave 254 nm) as well as a dedicated longwave Model UVL-56 Blak-Ray lamp (366 nm).? ?Surprisingly, I didn’t get any appreciable fluorescence, and no phosphorescence, from either of these mercury-vapor based lamps.? Only the LED-based flashlight seemed to elicit the phosphorescence.

?

Now for my question:? Would any of you fine gentlemen want to exercise the quest for knowledge to analyze some of this mystery calcite for trace element content to ascertain what might be leading to the phosphorescence?? Being calcite, one would expect Calcium, Sulphur, and Oxygen, but there must be some trace element (rare earth??) that is contributing to the fluorescence and/or phosphorescence?? I went back to the parking lot where the crushed cobble had been placed, and maybe only about a quarter of the cobbles I collected exhibited fluorescence/phosphorescence.? I was able to find several chunks of the ‘pure’ calcite (no green-gray matrix), and it too showed about a 25% to 30% of the number of pieces exhibiting fluorescence.? All of the stone looked similar and probably came form the same quarry, but only a fraction of it showed any fluorescence/phosphorescence.

?

Any takers?? I’d be happy to drop a chunk or two of the “mystery” calcite in the mail to anyone who might want to take a crack at running an XRF to look for anything unusual.? Drop me an email if you’re interested.

?

Thanks, and keep up the great work!

?

Ken Sejkora, WB0OCV

East Falmouth, MA

Email: kjsejkora@...

?

?

Geo

?

Geo

Ignore the nov

It’s?just there to organize my samples since changing settings?

nov is for November?

The one with lead water?control sample ?is?filter paper wet with clean?RO water?

Lead water is RO residue?

Am241 is for calibration check?

Taray

On Saturday, November 7, 2020, 11:37 PM, GEOelectronics@... wrote:

One more question, do you have a long time background test with no exciter or sample?

If not, please put that on your list of things to do, for same 2800 seconds or whatever long time you use.

Geo

---

From: "taray singh via groups.io" <sukhjez@...>
To: [email protected]
Sent: Saturday, November 7, 2020 4:51:28 AM
Subject: Re: [XRF] Chinese water filter analysis

Geo

I am not sure of the shifting downward trend.

But most of my low Z samples esp containing organics such C,H ,O or N tend to have scattering peaks at 13 ,16 ,20 and 50.

Their broad nature suggest they are Compton scattering .

Taray

On Saturday, November 7, 2020, 6:16 PM, GEOelectronics@... wrote:

Good work Taray. I was thinking the 3 large peaks were backscatter from the exciter source, but with your calibration they seem to be clearly shifted downward, do you have a theory?

Geo

---

From: "taray singh via groups.io" <sukhjez@...>
To: [email protected]
Sent: Saturday, November 7, 2020 12:07:34 AM
Subject: Re: [XRF] Chinese water filter analysis

Hi guys
Repeated this test with more sample? concentrate .
Sampling preparation is important for optimal results.
Soaking a filter paper direct works better than scanning through plastic containers.
This is not a clinical trial so issue of bias does not exist but to have an open mind.
The gains are improved this time.Further improvements via fine gain control will be attempted next time.
Slow learning curve...
Results are suggestive of lead in drinking water.
Suggestive? is good enough for affirmative action,
Don't drink stagnated water from taps.Flush before drinking,
Most of these heavy metals come from plumbing system.
Most publications on water lead? content point to near normal levels
Higher levels ones? will face hurdles before publication.
Thanks
Taray

One more question, do you have a long time background test with no exciter or sample?

If not, please put that on your list of things to do, for same 2800 seconds or whatever long time you use.

Geo

---

From: "taray singh via groups.io" <sukhjez@...>
To: [email protected]
Sent: Saturday, November 7, 2020 4:51:28 AM
Subject: Re: [XRF] Chinese water filter analysis

Geo

I am not sure of the shifting downward trend.

But most of my low Z samples esp containing organics such C,H ,O or N tend to have scattering peaks at 13 ,16 ,20 and 50.

Their broad nature suggest they are Compton scattering .

Taray

On Saturday, November 7, 2020, 6:16 PM, GEOelectronics@... wrote:

Good work Taray. I was thinking the 3 large peaks were backscatter from the exciter source, but with your calibration they seem to be clearly shifted downward, do you have a theory?

Geo

---

From: "taray singh via groups.io" <sukhjez@...>
To: [email protected]
Sent: Saturday, November 7, 2020 12:07:34 AM
Subject: Re: [XRF] Chinese water filter analysis

Hi guys
Repeated this test with more sample? concentrate .
Sampling preparation is important for optimal results.
Soaking a filter paper direct works better than scanning through plastic containers.
This is not a clinical trial so issue of bias does not exist but to have an open mind.
The gains are improved this time.Further improvements via fine gain control will be attempted next time.
Slow learning curve...
Results are suggestive of lead in drinking water.
Suggestive? is good enough for affirmative action,
Don't drink stagnated water from taps.Flush before drinking,
Most of these heavy metals come from plumbing system.
Most publications on water lead? content point to near normal levels
Higher levels ones? will face hurdles before publication.
Thanks
Taray

Good work Taray. I was thinking the 3 large peaks were backscatter from the exciter source, but with your calibration they seem to be clearly shifted downward, do you have a theory?

Geo

---

From: "taray singh via groups.io" <sukhjez@...>
To: [email protected]
Sent: Saturday, November 7, 2020 12:07:34 AM
Subject: Re: [XRF] Chinese water filter analysis

Hi guys
Repeated this test with more sample? concentrate .
Sampling preparation is important for optimal results.
Soaking a filter paper direct works better than scanning through plastic containers.
This is not a clinical trial so issue of bias does not exist but to have an open mind.
The gains are improved this time.Further improvements via fine gain control will be attempted next time.
Slow learning curve...
Results are suggestive of lead in drinking water.
Suggestive? is good enough for affirmative action,
Don't drink stagnated water from taps.Flush before drinking,
Most of these heavy metals come from plumbing system.
Most publications on water lead? content point to near normal levels
Higher levels ones? will face hurdles before publication.
Thanks
Taray

Good scan on the granite. Was this excited (XRF)? ?or only internal (Gamma Spectrum Analysis) mode?

Some of us have a particular interest in the Gamma Spec mode (no exciter, just the Si-PIN sensor) for different reasons and soon there will be a TOPIC to gather all those type reports and comments into a theme,

In that same thought, we constantly fight Cosmic Ray Muon excitation of? internal XRF in our probe shields.? That's why we uses graded? atomic weight layers, each of a lower Z to shield against those spontaneous characteristic X-Rays.

Note- if you want to insert an attached picture into the text area of a post, it must be done on the Groups.io vs email reply, when you load picture into the? attachment window, and before clicking the ADD button, click on the picture in the preview box and Ctl+C save it to your clipboard, then go ahead and push ADD button, which should return you to the text area. Once there, find a place for the picture and click on that space, then Ctrl+V paste it there. Supposedly the GROUPS.io resizes it for the email delivery.

On the email delivery pictures, is anyone having issues that the pictures are too large??? If so we can request that members resize them down to 640 X 480, which still leaves the attachment version full size for closer examination if needed.

Geo

---

From: "taray singh via groups.io" <sukhjez@...>
To: [email protected]
Sent: Thursday, November 5, 2020 8:35:03 AM
Subject: Re: [XRF] Uranium Ore , Depleted Uranium, Natural Uranium (Unat) Compared

Geo
Good topic.
Some? radioactive? ores are naturally link to certain elements.
Granite contains small amounts of Fe which can be measured by Si pin.
Here? is pic of my local granite showing Fe peaks

Taray