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Improving Mindat.orgQuestionable "Cyanotrichite" photo of the day

4th Jul 2006 17:41 UTCUwe Kolitsch Manager

http://www.mindat.org/picshow.php?id=64434

Looks more like radiating aggregates of acicular (elongate laths in fact) azurite which are well-known from Lavrion (e.g. http://www.mindat.org/picshow.php?id=10371)

4th Jul 2006 21:19 UTCMarius Utens

other possibility is serpierite

marius utens

5th Jul 2006 01:19 UTCAntonio Borrelli Expert

Hi Uwe,

I must admit that the deep blue color is unusual for cyanotrichite but the sprays are so tiny that I can't perform any test on them.

I could try with a drop of HCl to see if causes some fizzing but I'll end up spoiling this TN sized specimen.

I guess we should trust the dealer's label or instead I can delete the photo from the database.

Antonio

5th Jul 2006 06:01 UTCRobert Meyer Manager

Hi Antonio,

In my experience, Cyanotrichite from Lavrion is sometimes atypical--darker blue and more coarsely crystallized--as in your photograph. I did not doubt the identity of your specimen. The other Mindat photographs of Cyanotrichite from the Lavrion district bear that out.

You might still wish to get a single needle off of the specimen, and put a drop

of HCl on it an examine the reaction under the microscope.

Bob

5th Jul 2006 13:56 UTCPeter Andresen Expert

Just to switch subject a little, but still concerning the same photo...

When I saw the nice photo I immediatly paid attention to the odd looking yellow mineral that the cyanothrichite was partly sitting on... Do you have any idea what this is? And if you do, please add this information on the description, it kind of made the picture becoming as nice as it is.

This is a thought I often get looking at pictures here in Mindat, to often are accessory minerals worth mentioning left out of the description. This is sad, because it makes the picture a lot more interesting and informative when it's added...

Could it be an idea for our picture reviewers to have a standard e-mail message requesting such information, when there's obviously some interesting accessories? This of course only when the accessories are known...

Regards

Peter A

5th Jul 2006 14:22 UTCLefteris Rantos Expert

Peter,

I was thinking of the same thing... It's a light bluish mineral (see the interior of the aggregate) with some kind of tan-whitish surface alteration. However, these light blue crusts and bortyoids from Lavrion are often very difficult to identify. My guess is that it could be some Woodwardite-like mineral, but this is a mere guess.

Maybe Uwe could help a little more here?

Concerning the Cyanotrichite, thera are some azure-blue Cyanotrichites from Lavrion indeed. If it's acicular Azurite, the xls should be very elongated laths, not fine acicular as in Cyanotrichite. But I can't really tell from the photo.

Lefteris.

5th Jul 2006 14:41 UTCAntonio Borrelli Expert

Hi Peter,

I agree with your suggestion.

I always try to mention in my descriptions all the accessory minerals that can be seen in the pictures but in this case I do not have a clue of what the greenish blob may be.

Antonio

5th Jul 2006 15:33 UTCAntonio Borrelli Expert

I managed to take a strong close up of one of the xls spray.

http://img151.imageshack.us/my.php?image=picture14us.jpg

Which are your opinions? I think Uwe was right: they don't resemble to cyanotrichite.

Antonio

6th Jul 2006 13:50 UTCMarius Utens

when I see the close up and the greenish bleu colour and the elongated laths

form, I think its also possible serpierite

marius utens

6th Jul 2006 14:03 UTCPeter Andresen Expert

With it's bright deep-blue colour and the form of the crystals, I can't help thinking linarite...

Regards

Peter A

27th Oct 2006 14:39 UTCUwe Kolitsch Manager

This was also originally labeled (sold) as cyanotrichite, but turned out to be azurite:

http://www.mindat.org/photo-42322.html

I will change

http://www.mindat.org/picshow.php?id=64434

to azurite as well, but keep an explanatory note in the description.

27th Oct 2006 17:15 UTCKnut Eldjarn 🌟 Manager

I was also thinking about linarite or azurite when looking at the photo.

If Antonio could pry loose a microscopic fragment of the mineral and watch the reaction with HCl in a microscope he could probably distinguish between these two. Azurite would dissolve slowly with the formation of small bubbles of CO2 (depending on the HCl-concentration) - on linarite a white coating of lead-chloride would be formed. This can be a very useful and simple microchemical test.

Knut

28th Oct 2006 00:39 UTCAntonio Borrelli Expert

I performed the test with HCl that Robert and Knut have suggested with the result that a tiny fragment was completely dissolved.

In the end it is azurite.

Antonio

29th Oct 2006 13:54 UTCPeter Haas

How dilute was the HCl that you used ?

30th Oct 2006 00:09 UTCAntonio Borrelli Expert

15% HCl

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