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Identity HelpUK yellow needles

14th Jul 2012 18:13 UTCReiner Mielke Expert

This is the EDS results of some yellow acicular crystals that occur as inclusions in calcite. Does anyone have any idea what it might be? Ignore the Ni peak it is an artifact of poor electrical conductivity. Haven't attached a photo as the description says it all.

14th Jul 2012 18:55 UTCUwe Kolitsch Manager

Is the Ca peak (in part?) due to the calcite?

Locality?

14th Jul 2012 18:58 UTCReiner Mielke Expert

Yes the Ca peak is due to Calcite. The locality is the Frontier Mine in Silver Centre, Ontario. This is totally new for that locality. It is from a sample with abundant bismuthinite.

14th Jul 2012 20:58 UTCRonald John Gyllenhammer Expert

WAG: Something like Tundrite-(Ce)???? but doubtful at Frontier Mine.

14th Jul 2012 21:21 UTCReiner Mielke Expert

That is what I thought as well. REE minerals are known to occur in the Cobalt camp, I found Kainosite-Y at the Castle Mine in Gowganda and Jambor 1971 in describing the gangue mineralogy of the area mentions the presence of allanite and a bright red "unidentified yttrium silicate" from the Christopher mine.

14th Jul 2012 21:34 UTCReiner Mielke Expert

Found some more, this time as inclusions in quartz associated with calcite and bismuth.Will post a picture as soon as possible.

14th Jul 2012 22:45 UTCMaggie Wilson Expert

in quartz

FOV 3 mm - my first crack at the new camera/scope set up - it will improve, I promise!

15th Jul 2012 00:10 UTCReiner Mielke Expert

The crystals in the photo look brown in real life they are distinctly yellow. Don't know why it turned out that way?

15th Jul 2012 00:26 UTCRalph S Bottrill 🌟 Manager

Tundrite is possible, though you should see a Na peak.

15th Jul 2012 00:38 UTCReiner Mielke Expert

Kerry Day did the scan and he said "The lack of Na at this setting doesn’t concern me too much." Not sure what that means exactly, but the sodium peak would normally be at about 1.0 . He also suggested Tundrite.

15th Jul 2012 08:24 UTCRalph S Bottrill 🌟 Manager

The Na peak is usually relatively weak, especially when you have heavy elements present, but you normally see at least a blip if it's a major component, but instrument settings will affect this.

15th Jul 2012 18:24 UTCAmanda Hawkins

Maggie, judging from your photo they look exactly like Cacoxenite to me, but then I'm no expert on the scientific side.....

15th Jul 2012 19:29 UTCMaggie Wilson Expert

HI Amanda - that was my first guess when I saw the crystals, but the EDS takes us down an entirely different road...

15th Jul 2012 21:18 UTCBig V

could it be a variety of tundrite previously undiscovered? I mean, "K" could easily replace "Na". They're from the same group on the periodic table and they have the same valence as well.

16th Jul 2012 09:09 UTCPeter Haas

"I mean, "K" could easily replace "Na". They're from the same group on the periodic table and they have the same valence as well."

They do not have the same size and therefore, K⁺ won't replace Na⁺ that easily.

18th Jul 2012 00:09 UTCReiner Mielke Expert

Hello Big V,

Interesting point, however analysis of Russain material shows as much as 9 mole% K in the Na position. That could account for the peak. Since K is a much heavier element than Na I would expect it to show up better on EDS.

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