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Identity HelpMonazite or ?
31st Jan 2012 02:44 UTCJames Christopher
I got this at a locality that is not listed at all, a large cavity in Pikes Peak granite that mostly has extremely large quartz crystals. Hematite coatings are also present extensively, another unknown and much more radioactive mineral, and what we believe is columbite/tantalite.
This one has the color better shown in the first photo. The second shows the shape in general better. SG is 5.45, hardness 5.5-6. It is slightly radioactive, but nowhere near what the other unknown is(which I may post at a later time) Any guesses as to this one? It does seem transparent in the one uncoated brown section in the first photo.
31st Jan 2012 03:16 UTCCraig Mercer
Definitely everything points to it being Monazite. Gadolinite one of the associates is quite similar, just a little harder.
Anyway goodluck mate,
Craig.
5th Feb 2012 01:32 UTCJames Christopher
5th Feb 2012 05:46 UTCJames Christopher
Literature for Bastnäsite: 4-4.5
That would rule it out.
But - all other attributes are right: color reddish brown luster waxy translucent uneven fracture tabular parting on 001, in that direction prismatic, hexagonal
Here is the Raman spectrum. The 1100 cm^-1 peak is carboate. When you compare with the RRUFF database note that there is wavelength and polarization dependence which determines the relative peak intensity.
In general, our spectrum is a very high good spectrum with narrow peak, and well defined modes. This indicates a well defined crystal.
This one comes close, just was acquired with lower resolution. http://rruff.info/bastnasite/display=default/R060359
That would settle it if .... hardness ... and low radioactivity.
I read 20 g pieces have 14 kBq. My 20 g piece held to one side of crystal registers 20-30 cps. Let's make a first order estimate, I capture 1/6th then total would make <200 cps.
5th Feb 2012 20:02 UTCRudy Bolona Expert
Is the entire specimen mono-mineralic? I found something very similar to this a couple of years ago In Pikes Peak granite and it still remains a mystery to me.
6th Feb 2012 01:12 UTCJames Christopher
15th Feb 2012 10:49 UTCRalph S Bottrill 🌟 Manager
15th Feb 2012 13:33 UTCJames Christopher
24th Feb 2012 23:34 UTCJames Christopher
Ok, a more trustworthy semiquantative XRF. Raman is going to be redone as it indicates a carbonate. Any new ideas?
25th Feb 2012 01:52 UTCRudy Bolona Expert
Did you find multiple specimens of this mineral?
25th Feb 2012 02:15 UTCJames Christopher
25th Feb 2012 19:51 UTCPavel Kartashov Manager
I can't to imagine that your mineral from photo is gadolinite-(Ce) with 14 mas.% of Fe. There must be some misunderstanding. in any case it would be better to check P content instead of Ni, Co, Rb and Cs.
25th Feb 2012 21:47 UTCRalph S Bottrill 🌟 Manager
26th Feb 2012 00:28 UTCPavel Kartashov Manager
What about biraite, I would be very surprised to found it in such situation. Besides that total REE content of the mineral is too low for biraite.
High Al and K+Na concentrations puzzling me. May be it is something completely new, if it isn't mixture? Here is very strange combination of fresh appearance of mineral and bad analyses typical for mixtures...:-S
26th Feb 2012 14:49 UTCJames Christopher
12th Mar 2012 04:40 UTCJames Christopher
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