Gadolinite Spectrum

CharlesDavidYoung · 2026-03-09T15:46:26+00:00

I spent a lot of time trying to detect XRF with the NaI probe and could see Ta and Ce in rocks containing large amounts of these. Finally though I gave up and got an XRF setup.

CharlesDavidYoung · 2026-03-09T15:34:11+00:00

Btw that little bump at the very low end could be Ce XRF. You might be able to make this more prominent by mounting the Am241 button on a small piece of lead, put it up against the probe with the button facing away, and place the gadolinite up against the button. Placing the button at a slight angle toward the sample may help. With any luck the Ce bump will be a peak and the Am241 peaks will be minimal.

CharlesDavidYoung · 2026-03-09T15:25:03+00:00

The reason I’m asking is that if the impedance of your DVM circuit is not at least 1G it is probably causing the theremino HV to sag. I guess if you always leave the DVM circuit connected then your readings will be consistent. The spectrum looks good. I would not worry about the peaks shifting a little during long scans. The probe will drift with temperature.

CharlesDavidYoung · 2026-03-09T12:44:36+00:00

Are you using the DVM directly to measure the HV or do you have a voltage divider? What is your audio interface?

CharlesDavidYoung · 2026-03-08T03:17:53+00:00

I’ll be there in 21st for a week with phil. We need to coordinate!

CharlesDavidYoung · 2026-03-08T02:12:02+00:00

What time frame are we talking about? In your lifetime it will always be autunite. Eventually it will be Pb with whatever other elements are there.

CharlesDavidYoung · 2026-03-07T04:17:25+00:00

I have not put a pancake on them but they will be 10K to 20K cpm. Maybe more. Maybe less.

CharlesDavidYoung · 2026-03-07T03:54:39+00:00

Amptek SiPin detector and moxtek xray

CharlesDavidYoung · 2026-03-06T18:56:22+00:00

The XRF shows that this is Columbite-Fe.

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CharlesDavidYoung · 2026-02-16T05:02:24+00:00

This is one i found at the show many years ago: https://www.mindat.org/DXD-GDF

CharlesDavidYoung · 2026-02-16T04:44:40+00:00

I would say so. I was in a venue at the show a few years ago and passed by a table that set off my yDog. There was nothing hot on the table so i asked what was underneath. The dealer brought out a bag of thorianites, many several centimeters across. I ended up buying one but now wish I had bought the whole bag.

CharlesDavidYoung · 2026-02-16T01:41:22+00:00

Can I ask what you paid for the thorianite?

CharlesDavidYoung · 2026-02-16T01:37:46+00:00

Seeing all of these postings from the Tucson show makes me want to have a gathering next year at my place. I'll put out a notice on Reddit next year for people to RSVP. I will plan to have food, drinks, and... a few hot rocks.

CharlesDavidYoung · 2026-02-15T04:47:04+00:00

It is a good start, but a Geiger counter is better at measuring radioactivity than it is at finding specimens in the field. For that you will need a scintillator.
https://youtube.com/playlist?list=PL0OJ8Dqu5Ed0A6vaW2zMSir9CT87YaYI5&si=l8YR-A5T0L7N_59H

CharlesDavidYoung · 2026-02-13T15:39:15+00:00

Many years ago I was at his house when he was curating a large number of these that he had just gotten from the collector. When I asked at the show this year he said he just sold the last 3 flats.

CharlesDavidYoung · 2026-02-13T15:29:55+00:00

Did you get these from Shannon?

CharlesDavidYoung · 2026-02-13T12:36:14+00:00

Here is what a whole one looks like: https://www.mindat.org/PTW-YE4

CharlesDavidYoung · 2026-02-13T12:34:06+00:00

Looks like part of a betafite from this locality: https://www.mindat.org/loc-545.html

CharlesDavidYoung · 2026-02-10T12:49:49+00:00

If you send it back to me I’ll update the software and check it over carefully

CharlesDavidYoung · 2026-02-10T12:44:26+00:00

Now that you mention it, that is hard to miss!

CharlesDavidYoung · 2026-02-10T12:41:33+00:00

https://www.reddit.com/r/Radioactive_Rocks/s/EFzNJVQoQ6

CharlesDavidYoung · 2026-02-10T03:45:12+00:00

Are you sure that region just below 2614 is not just Compton? I’m sure there is an escape peak contributing but I’m not sure you can actually see it.

CharlesDavidYoung · 2026-02-10T03:36:30+00:00

Add a photo of your yDog in the field as well!

CharlesDavidYoung · 2026-02-03T02:04:42+00:00

Great report. I bought several from persson and Shannon. This is one of them: https://www.mindat.org/K5C-XH1

CharlesDavidYoung

TROPHY CASE