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Oddities from Brandberg, Namibia
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Pierre Joubert




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PostPosted: Feb 23, 2014 13:53    Post subject: Oddities from Brandberg, Namibia  

While cleaning crystals, I noted one damaged crystal with a most unusual included crystal. I assume, that as I have never seen something like this from Brandberg before, it must be a rarity from this area, especially the size. There are no similar crystals included. The 'unknown' crystal appears to be square (more flat than square). Any ideas would be welcome.


P1280071.JPG
 Description:
Quartz with unknown inclusion.
Brandberg, Namibia
59 x 31 x 29 mm
The included crystal is approx. 15 mm long
 Viewed:  19331 Time(s)

P1280071.JPG



P1280072.JPG
 Description:
Quartz with unknown inclusion.
Brandberg, Namibia
59 x 31 x 29 mm
 Viewed:  19329 Time(s)

P1280072.JPG



P1280074.JPG
 Description:
Quartz with unknown inclusion.
Brandberg, Namibia
59 x 31 x 29 mm
Photo taken in artificial light.
 Viewed:  19342 Time(s)

P1280074.JPG



P1280061.JPG
 Description:
Unknown crystal
Brandberg, Namibia
Approx. 15 mm long
 Viewed:  19328 Time(s)

P1280061.JPG



P1280063.JPG
 Description:
Unknown crystal
Brandberg, Namibia
Approx. 15 mm long
Same as above
 Viewed:  19352 Time(s)

P1280063.JPG



P1280066.JPG
 Description:
Unknown crystal
Brandberg, Namibia
Approx. 15 mm long
Last 3 photos taken in sunlight.
 Viewed:  19329 Time(s)

P1280066.JPG



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PostPosted: Feb 23, 2014 18:09    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

such inclusions have been reported in alpine quartz crystals, but their exact nature often remained uncertain. It was suggested that they were possibly anhydrite or scapolite, that was either pseudomorphosed (for instance by muscovite), or dissolved to leave a hollow tube (which might be stained by a thin inner coating)
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PostPosted: Feb 24, 2014 00:32    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Do you know what other associated minerals came out of that pocket or nearby pockets? The associated minerals might give you a clue as to the mineralogy of the immediate area. Marv
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PostPosted: Feb 24, 2014 01:17    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

cascaillou wrote:
such inclusions have been reported in alpine quartz crystals, but their exact nature often remained uncertain. It was suggested that they were possibly anhydrite or scapolite, that was either pseudomorphosed (for instance by muscovite), or dissolved to leave a hollow tube (which might be stained by a thin inner coating)


Hi Cascaillou. I also considered the possibility that the original crystal dissolved and left a perfect cavity which in turn was filled with another mineral, possibly even clay. The small black bits of mineral could be either hematite or even epidote (more likely the first). This appears to be sitting directly on the surface of the strange included crystal.

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PostPosted: Feb 24, 2014 01:25    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

marvsT/Nminerals wrote:
Do you know what other associated minerals came out of that pocket or nearby pockets? The associated minerals might give you a clue as to the mineralogy of the immediate area. Marv


Hi Marv. The associated minerals common to this direct area are feldspar,calcite, prehnite, epidote, analcime, hematite(mostly as small inclusions). There are also other minerals but these are uncommon. Somewhere, I have a quartz crystal or two from this area that has a few small yellowish needle like inclusions. I must search for them; perhaps there is a link between the two.

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PostPosted: Feb 24, 2014 01:37    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

See a list of minerals from Mindat. http://www.mindat.org/loc-4534.html

The mineral specimens from Goboboseb rarely has more than 4 of these attached. The most common is calcite, prehnite, feldspar, epidote and analcime. Inclusions are usually small flakes of hematite, minute epidote crystals, or minute prehnite crystals.

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PostPosted: Feb 24, 2014 01:56    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

could it be metallic?
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PostPosted: Feb 24, 2014 02:08    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Very probably it is anhydrite. It has been cited, as inclusion, in some Swiss quartzes.
As example, you can see pages 140-142 of the book: Hyrsl, J., Niedermayr, G. 2003. Magic world: inclusions in quartz. Bode Verlag.
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PostPosted: Feb 24, 2014 02:27    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Carles Curto wrote:
Very probably it is anhydrite. It has been cited, as inclusion, in some Swiss quartzes.
As example, you can see pages 140-142 of the book: Hyrsl, J., Niedermayr, G. 2003. Magic world: inclusions in quartz. Bode Verlag.

Hi Carles. Cascaillou shares your thoughts 'such inclusions have been reported in alpine quartz crystals, but their exact nature often remained uncertain'. Can this book be viewed on line? If indeed, do you have a link.? I see anydrite is the dehydrated form of Gypsum. This could easily dissolve, espescially if the one end is open (which is the case here). The cavity can then be filled. However way you look at it, it is a very unusual occurance at Goboboseb.

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PostPosted: Feb 24, 2014 03:51    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

I don't know if the book is on line (I suppose not).

Anhydrite, even considering it, genetically, a dehydrated form of gypsum, is a different species, with a very different structure (orthorhombic, very frequently with pseudotetragonal shape). I don't really know if, in your case, you have anhydrite crystals, empty geometric channels or a complete substitution by another mineral. (in fact we don't know if it is really anhydrite).

to be clearer, I add some images and the complete English text (the book was published in German-English) of Hyrsl and Niedermayr.

I hope Jaroslav and Gerhard excuse me the use of these images.



anhydrite010.jpg
 Description:
Brazil. 2,5 cm. (inclusion)
 Viewed:  19130 Time(s)

anhydrite010.jpg



anhydrite011.jpg
 Description:
St. Gottard, Switzerland. 1.cm (edge)
 Viewed:  19118 Time(s)

anhydrite011.jpg



anhydrite012.jpg
 Description:
Lubudi, Congo
2 cm.
(a detail of the published image.
 Viewed:  19150 Time(s)

anhydrite012.jpg



anhydrite014.jpg
 Description:
 Viewed:  19121 Time(s)

anhydrite014.jpg



anhydrite015.jpg
 Description:
 Viewed:  19114 Time(s)

anhydrite015.jpg



anhydrite016.jpg
 Description:
 Viewed:  19161 Time(s)

anhydrite016.jpg


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PostPosted: Feb 24, 2014 04:18    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Carles Curto wrote:
I don't know if the book is on line (I suppose not).

Anhydrite, even considering it, genetically, a dehydrated form of gypsum, is a different species, with a very different structure (orthorhombic, very frequently with pseudotetragonal shape). I don't really know if, in your case, you have anhydrite crystals, empty geometric channels or a complete substitution by another mineral. (in fact we don't know if it is really anhydrite).

to be clearer, I add some images and the complete English text (the book was published in German-English) of Hyrsl and Niedermayr.

I hope Jaroslav and Gerhard excuse me the use of these images.


Fantastic information Carles. Thank you very much. In this case the void appears to be filled with clay. What an unusual occurance, especially from Brandberg (Goboboseb area)

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PostPosted: Feb 24, 2014 04:33    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

My data is also from the same book.
At the beginning of the book (in the part dealing about fluid inclusions and hollow cavities), there's another paragraph about those tubes. It is explained that while anhydrite and scapolite have been idntified as inclusions in quartz, the nature of these hollow tubes wasn't confirmed for sure, but hypothesized to be anhydrite or scapolite casts (after dissolution)
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PostPosted: Feb 24, 2014 04:53    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

cascaillou wrote:
My data is also from the same book.
At the beginning of the book (in the part dealing about fluid inclusions and hollow cavities), there's another paragraph about those tubes. It is explained that while anhydrite and scapolite have been idntified as inclusions in quartz, the nature of these hollow tubes wasn't confirmed for sure, but hypothesized to be anhydrite or scapolite casts (after dissolution)


Thanks Cascaillou. Any more info will be welcome.

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PostPosted: Feb 24, 2014 07:11    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Hi Pierre

I've never seen anything like that in the crystals from the Goboboseb & I've looked at 1000s with a loupe, I get mesmerized by the inclusions :0) I've never seen Prehnite included either.

Nice crystal & a keeper.
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PostPosted: Feb 24, 2014 07:33    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Debbie Woolf wrote:
Hi Pierre

I've never seen anything like that in the crystals from the Goboboseb & I've looked at 1000s with a loupe, I get mesmerized by the inclusions :0) I've never seen Prehnite included either.

Nice crystal & a keeper.


Hi Debbie. This year has been a mad one, I would love to sit down some day and add to the thread on quartz inclusions. I hope to photograph some prehnite inclusions as well. My favourite is the perfect negative crystals. How they form is an absolute mystery. Thanks for your input:-)

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PostPosted: Feb 24, 2014 08:20    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

I look forward to seeing the photos someday.
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PostPosted: Feb 24, 2014 14:50    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Pierre, if you're interested in inclusions you will like:

Magic World: Inclusions in Quartz (by Jaroslav Hyrsl and Gerhard Niedermayr)
This book is only about inclusions in quartz

Photoatlas of Inclusions in Gemstones, 3 volumes (by Eduard J. Gubelin and John I. Koivula)
All three volumes are excellent, and each of these cover all kind of inclusions found in many different gemstones. But you might be first interested in the second volume which has 124 pages about inclusions in quartz.

The Microworld of Diamonds (by John I. Koivula)
This one is only about inclusions in diamonds

Keep those books in mind for your birthday!
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PostPosted: Feb 25, 2014 00:48    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

cascaillou wrote:
Pierre, if you're interested in inclusions you will like:

Magic World: Inclusions in Quartz (by Jaroslav Hyrsl and Gerhard Niedermayr)
This book is only about inclusions in quartz

Photoatlas of Inclusions in Gemstones, 3 volumes (by Eduard J. Gubelin and John I. Koivula)
All three volumes are excellent, and each of these cover all kind of inclusions found in many different gemstones. But you might be first interested in the second volume which has 124 pages about inclusions in quartz.

The Microworld of Diamonds (by John I. Koivula)
This one is only about inclusions in diamonds

Keep those books in mind for your birthday!


Hi Cascaillou. I am indeed interested in quartz inclusions (very much so). I will join a club just for that. I will keep the books in mind and see if I can order them somewhere Regards:-)

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PostPosted: Apr 20, 2014 05:27    Post subject: Re: Unknown crystal in Brandberg quartz crystal  

Hi Jordi. Is it possible to change the topic of this thread to' Oddities from Brandberg, Namibia'? This will allow me to show a few more different unusual minerals, most of which I do not know the identity of. By voorbaat dank!
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PostPosted: Apr 20, 2014 11:52    Post subject: Re: Oddities from Brandberg, Namibia  

Pierre Joubert wrote:
Hi Jordi. Is it possible to change the topic of this thread to' Oddities from Brandberg, Namibia'? This will allow me to show a few more different unusual minerals, most of which I do not know the identity of. By voorbaat dank!

Done!
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