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Mystery mineral from Muzo, Colombia
  
  Index -> What is it? - Where is it from?
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Bergur_E_Sigurdarson




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PostPosted: Feb 19, 2019 17:42    Post subject: Mystery mineral from Muzo, Colombia  

Those two specimens pictured were sold to me in Muzo, by a local seller that was adament that they were from the Muzo mine area itself not nearby mines)

He thought it was hematite, and I bought them as a curiousity. But as I inspected them further they are not black, but very dark, and yet transparent.
Colour changes between green and blue depending on angle.

Both specimens are btw 3-4cm on the longest side so crystals are smaller, around 1,5cm the largest.

( I picked the best photos from a few I took, that hopefully show what is needed, but I can take more with instruction on what feature to capture )

They are both very fragile and one has already had one crystal segment crumble as I touched it (making hardness determination very difficult)



muzo-mystery-01.jpg
 Mineral: Hematite?
 Locality:
Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia
 Dimensions: Appx. 3-4cm
 Description:
 Viewed:  440 Time(s)

muzo-mystery-01.jpg



muzo-mystery-02.jpg
 Mineral: Hematite?
 Locality:
Muzo mining district, Western Emerald Belt, Boyacá Department, Colombia
 Dimensions: Appx. 3-4cm
 Description:
 Viewed:  438 Time(s)

muzo-mystery-02.jpg


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Bob Carnein




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PostPosted: Feb 19, 2019 17:50    Post subject: Re: Mystery mineral from Muzo, Colombia  

From your description, I think it might be vivianite.
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kushmeja




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PostPosted: Feb 19, 2019 18:00    Post subject: Re: Mystery mineral from Muzo, Colombia  

I was also thinking vivianite based on the appearance and brittleness, but I can't find any references to vivianite coming from anywhere in that area.
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Bergur_E_Sigurdarson




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PostPosted: Feb 19, 2019 18:05    Post subject: Re: Mystery mineral from Muzo, Colombia  

I did look at photos of all "known" minerals listed on Mindat for Muzo, and found nothing remotely similar.

The miners there are tho primarily looking for Emeralds, and sometimes keep Quartz when they find it.... most other stuff is discarded immediately.

So a dark and unappealing thing like this might just get lost most of the time in the dark dust of the shale in the mining area (I even struggle with cleaning it from my clothes after visiting :-P )
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Bob Carnein




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PostPosted: Feb 19, 2019 19:46    Post subject: Re: Mystery mineral from Muzo, Colombia  

If you search "vivianite from Colombia" and look at the illustrations, there are a couple of not-very-spectacular vivianites supposedly from the Muzo mine. Bolivia is better known for fine vivianites; your specimen probably wouldn't qualify as "fine".
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nicu




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PostPosted: Feb 20, 2019 06:55    Post subject: Re: Mystery mineral from Muzo, Colombia  

Not every salesman is a mineral connoisseur. Even less likely a collector or the rock hunter ..... the matrix looks like it was Vivianite; however, for a long time, it was exposed to intense light ...
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Bergur_E_Sigurdarson




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PostPosted: Feb 20, 2019 08:53    Post subject: Re: Mystery mineral from Muzo, Colombia  

After looking at Vivianite on Mindat and as suggested a search of that with locality did turn up some similar pieces I think this is indeed Vivianite.

Definetiley not a fine specimen, but I like adding curiousities to my collection and now can hope to find a better specimen later :-)

Thanks all who added their input for your help!
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Pete Richards
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PostPosted: Feb 20, 2019 09:06    Post subject: Re: Mystery mineral from Muzo, Colombia  

Check an older mineralogy text (e.g. Dana's System 7th edition) for simple tests to confirm vivianite. It is very soft, it is soluble in acids, and it s should turn white and exfoliate in the heat of a torch. And other tests....
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