Re: Brannerite! (or is it?)
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Sorry that I forgot to attach the .mca file.? Here it is.
So I went back to the dealer today.? Gunnar Faerber is a highly experienced collector and has his own analysis equipment.? Unfortunately, between his heavy German accent and his very technical explanations I was somewhat lost as he was assuring me that this was definitely brannerite based on the latest definitions.? Also, mindat has the following for brannerite:
UTi2O6
Often contains impurities; an older formula is (U4+,REE,Th,Ca)(Ti,Fe3+,Nb)2(O,OH)6.
So Gunnar was not at all surprised to see the large amount of Nb.? He promised to send me his analysis so perhaps that will further enlighten.? In the meanwhile, I am going to assume that this is indeed brannerite.? BTW he said that betafite is an old discredited term and should not be used.
Charles
On Mon, Feb 10, 2020 at 8:48 PM WILLIAM S Dubyk < sdubyk@...> wrote:
If you need a chunk or monazite, let me know, I've got plenty of it.
Cool Steve. I don't follow the fine details but get the idea.
We appreciate your input.
George?
----- Original Message -----
From: WILLIAM S Dubyk < sdubyk@...>
To: [email protected]
Sent: Mon, 10 Feb 2020 21:58:52 -0500 (EST)
Subject: Re: [XRF] Brannerite! (or is it?)
You are correct Geo, those are not very accurate. Charles ran a specimen of xenotime from Madagascar that I had in my collection for years, a rather expensive one. It may have been from Madagascar so that part may be correct, but the x-ray indicated it
was likely monazite. Not happy about that but oh well. Yes, lots of thorium in the US, probably mostly as monazite, the Ce-Th phosphate. Thorium is almost always in the +4 state, whereas U is commonly in the +4 and +6 state. That indicates that U can also
form oxidized minerals, but Th does not. So Th minerals commonly contain U, and unoxidized primary U minerals also contain Th. When you get to the oxidized +6 U minerals however, they are very pure U with virtually no Th. So if you want a good pure U standard,
get an oxidized U mineral like meta autunite or something.?
Steve
haha. I've heard stories about the voracity of those rock-shop labels.?
Hey mineral guys, a question. How common is thorium in USA? Does it always come with U or is it also alone? Thanks
Geo>K0FF
I picked this up yesterday.? It was interesting because Brannerite
UTi2O6
is supposed to be high in Ti and less so in Ta and Nb like betafites (Ca,Na,U)2(Ti, Nb,Ta)2O6Z(OH).? However, this specimen has much more Nb than anything else.? It is going back to the dealer today with this scan so he can label it correctly.
Charles
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