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Mathias
Joined: 01 Apr 2018
Posts: 148
Location: Vlodrop
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Posted: Sep 22, 2024 06:16 Post subject: Verdelite & Quartz ? |
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Some time ago I've purchased a specimen with the label:
Verdelite & Quartz, Taquaral, Minas Gerais.
It is like a large green Verdelite crystal but the inside of it completely consists of presumably Quartz. Has anyone ever seen such similar specimen? The interior, presumably Quartz, doesn't really have the appearance of Quartz. But perhaps it is.
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Tobi
Site Admin
Joined: 07 Apr 2009
Posts: 4187
Location: Germany
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Posted: Sep 22, 2024 08:39 Post subject: Re: Verdelite & Quartz ? |
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Mathias wrote: | [...]It is like a large green Verdelite crystal but the inside of it completely consists of presumably Quartz. Has anyone ever seen such similar specimen? The interior, presumably Quartz, doesn't really have the appearance of Quartz. But perhaps it is. | Hi Mathias, yes, I have seen similiar pieces from Brazil: The Urubu Mine produced green tourmalines that are hollow and have an interior of quartz.
Here's information about that mine: https://www.mindat.org/loc-7723.html
Maybe there are other localities in Brazil where this happened to the elbaite. Maybe your specimen is from Urubu. Anyway, it is possible that quartz replaces the core of an elbaite crystal, so you were correct in your assumption.
Regards
Tobi
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Mathias
Joined: 01 Apr 2018
Posts: 148
Location: Vlodrop
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Posted: Sep 22, 2024 09:45 Post subject: Re: Verdelite & Quartz ? |
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Hi Tobi thanks, this indeed seems plausible.
I wonder how this happens, from the inside to the outside it pseudomorphs into Quartz, as it seems. What would be the mechanism behind this metamorphosis?
Thanks again,
Mathias
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Tobi
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Joined: 07 Apr 2009
Posts: 4187
Location: Germany
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Posted: Sep 23, 2024 05:44 Post subject: Re: Verdelite & Quartz? |
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Mathias wrote: | Hi Tobi thanks, this indeed seems plausible.
I wonder how this happens, from the inside to the outside it pseudomorphs into Quartz, as it seems. What would be the mechanism behind this metamorphosis?
Thanks again, Mathias | To be honest, I have no idea about the details of this mechanism. You can ask me a lot of things concerning mineral collecting and localities, but not about the chemistry and the physics of crystal growth, I'm sorry.
But I know there are several people here in this forum with a lot of specialist knowledge about this scientific aspect of the hobby. So maybe you'll get an answer, I would also be interested to know how and why this happens.
Regards
Tobi
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lluis
Joined: 17 Nov 2006
Posts: 717
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Posted: Sep 23, 2024 12:49 Post subject: Re: Verdelite & Quartz ? |
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Just a small question....
I saw in the link that Tobi provided, that the pseudomorph is "fibrous quartz", which makes me easier to understand pseudomorphing.
But in the example presented, I am unable to see "fibrous".
I see more a compact mineral..
May anyone of listizens bring me light on that? It is fibrous or it is compact?
With best wishes
Lluís
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John S. White
Site Admin
Joined: 04 Sep 2006
Posts: 1298
Location: Stewartstown, Pennsylvania, USA
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Posted: Sep 24, 2024 14:56 Post subject: Re: Verdelite & Quartz ? |
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Sure looks like tourmaline to me. Hollow tourmalines are common so quartz-filled tourmalines are known.
_________________ John S. White
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Bob Morgan
Joined: 18 Jan 2018
Posts: 234
Location: Savannah, Georgia
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Posted: Sep 24, 2024 15:50 Post subject: Re: Verdelite & Quartz ? |
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Mike Wise showed a photo of a spectacular specimen at the Mineral Section of the Rochester Academy of Science a few years ago. It was a several inches tall green Tourmaline with a large well developed quartz crystal nested in the middle.
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