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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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Posted: Apr 20, 2014 14:15 Post subject: Re: Oddities from Brandberg, Namibia |
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Jordi Fabre wrote: | 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! |
Thank you very much Jordi! I will continue with a specimen consisting of Quartz, Calcite, Epidote and an unknown mineral, perhaps Chrysocolla. Whatever it is, it is something I have never seen from Brandberg area.
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Quartz, calcite, epidote, and an unknown mineral. Brandberg, Namibia 40 x 38 x 28 mm The calcite has two types of crystalization. |
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Quartz, calcite, epidote and an unknown mineral. Brandberg, Namibia 40 x 38 x 28 mm |
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Quartz, calcite, epidote, and an unknown mineral. Brandberg, Namibia 40 x 38 x 28 mm same as above. |
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unknown mineral on quartz Brandberg, Namibia F.O.V. approximately 9 mm |
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unknown mineral Brandberg, Namibia F.O.V approximately 9 mm |
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unknown mineral Brandberg, Namibia F.O.V approximately 9 mm |
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_________________ Pierre Joubert
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Pierre Joubert
Joined: 09 Mar 2012
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Location: Western Cape
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Posted: Dec 02, 2014 10:13 Post subject: Re: Oddities from Brandberg, Namibia |
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Here is a quartz crystal with a few gas bubbles captured in water, gas inclusions and some unusual crystal inclusions. My guess is that it is feldspar or dolomite. I do not know what the green mineral is. What do you think?
I do not agree with Brandberg being part of the Erongo region. It may be geographically correct but it is confusing as the two areas yield a different variety of mineral species and it is a distance from each other. Erongo itself has a number of subdivision areas like Spitzkoppe, Neu Scwaben, Karibib and off course, the Erongo mountains.
Mineral: | Quartz with unknown inclusions. |
Dimensions: | 53 x 26 x 20 mm |
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Mineral: | Quartz with unknown inclusions. |
Locality: | Goboboseb Mountains, Brandberg area, Erongo Region, Namibia | |
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Dimensions: | F.O.V. about 10 x 09 mm |
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Mineral: | Quartz with unknown inclusions. |
Locality: | Goboboseb Mountains, Brandberg area, Erongo Region, Namibia | |
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Dimensions: | F.O.V. about 10 x 09 mm |
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_________________ Pierre Joubert
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Pierre Joubert
Joined: 09 Mar 2012
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Posted: Dec 03, 2014 02:43 Post subject: Re: Oddities from Brandberg, Namibia |
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I found another crystal with the same inclusions; possibly from the same batch.
Mineral: | Quartz with unknown inclusions. |
Locality: | Brandberg area, Erongo Region, Namibia | |
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Dimensions: | F.O.V approximately11 x 08 mm |
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22245 Time(s) |
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_________________ Pierre Joubert
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ploum
Joined: 12 Nov 2007
Posts: 1393
Location: Near Annecy
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Posted: Dec 03, 2014 03:22 Post subject: Re: Oddities from Brandberg, Namibia |
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I think hematite for inclusion
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Pierre Joubert
Joined: 09 Mar 2012
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Posted: Dec 03, 2014 03:50 Post subject: Re: Oddities from Brandberg, Namibia |
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ploum wrote: | I think hematite for inclusion |
Thank you. I am sorry, I should have been more specific. I am referring to the white cubic or triclinic(?) crystals. Best regards.
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Martin Rich
Joined: 15 Aug 2013
Posts: 127
Location: Lower Austria
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Posted: Dec 03, 2014 16:23 Post subject: Re: Oddities from Brandberg, Namibia |
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Hello Pierre!
The white crystals could be adularia with minor green coating of a chlorite mineral.
Martin
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Pierre Joubert
Joined: 09 Mar 2012
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Location: Western Cape
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Posted: Dec 04, 2014 01:47 Post subject: Re: Oddities from Brandberg, Namibia |
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Martin Rich wrote: | Hello Pierre!
The white crystals could be Adularia with minor green coating of a Chlorit mineral.
Martin |
Thank you Martin. You are most likely right.
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marco campos-venuti
Joined: 09 Apr 2014
Posts: 207
Location: Sevilla
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Posted: Dec 09, 2014 07:39 Post subject: Re: Oddities from Brandberg, Namibia |
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The shape reminds me more of a carbonate, such as calcite, siderite, or dolomite.
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Pierre Joubert
Joined: 09 Mar 2012
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Posted: Dec 09, 2014 07:58 Post subject: Re: Oddities from Brandberg, Namibia |
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marco campos-venuti wrote: | The shape remembers more of a carbonate, as calcite, siderite, dolomite. |
Hi Marco. Thank you for your interest. I found that dolomite and feldspar can be so similar when it comes to inclusions. Perhaps it is dolomite.
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Jordi Fabre
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Posted: Dec 09, 2014 08:25 Post subject: Re: Oddities from Brandberg, Namibia |
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marco campos-venuti wrote: | The shape remembers more of a carbonate, as calcite, siderite, dolomite. |
Probably not inside the Quartz due the formation temperature of the Quartz. A feldspar sounds more reasonable.
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Pierre Joubert
Joined: 09 Mar 2012
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Location: Western Cape
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Posted: Dec 09, 2014 10:10 Post subject: Re: Oddities from Brandberg, Namibia |
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Jordi Fabre wrote: | marco campos-venuti wrote: | The shape remembers more of a carbonate, as calcite, siderite, dolomite. |
Probably not inside the Quartz due the formation temperature of the Quartz. A feldspar sounds more reasonable. |
Hi Jordi. Now I will attempt to prove you wrong :-) Till then I am happy to settle with Martin Rich's initial observations. Regards.
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marco campos-venuti
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Posted: Dec 10, 2014 06:33 Post subject: Re: Oddities from Brandberg, Namibia |
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Dolomite in quartz is very common in Brazil. Here is an example.
Quartz can crystallize in a wide range of temperatures. But the crystal shape of feldspars from the Celsian-Hyalophane series is very similar to rhombohedral carbonates.
Mineral: | dolomite in quartz |
Locality: | Minas Gerais, Brazil | |
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Dimensions: | 62 mm |
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Jordi Fabre
Overall coordinator of the Forum
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Posted: Dec 10, 2014 11:37 Post subject: Re: Oddities from Brandberg, Namibia |
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marco campos-venuti wrote: | Dolomite in quartz is very common in Brazil. Here an example.
Because quartz can crystallize in a wide range of temperatures. |
True Marco, thank you to point out but I believe the deposits of Brandberg area are related with high-temperature geological processes.
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cascaillou
Joined: 27 Nov 2011
Posts: 251
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Posted: Dec 12, 2014 11:25 Post subject: Re: Oddities from Brandberg, Namibia |
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Hi,
concerning the identity of those white crystals, you could try:
-LW and SW UV (if any fluorescence, report intensity and color of fluorescence, and also check in complete darkness if there's any residual phosphorescence once the UV have been cut)
-check the transparent ones for doubling of their inclusions/edges (with a good microscope)
-check for cleavages or any characteristic twinning under the microscope
-you could also try crossed polars under the microscope, checking for lamellar twining, if any.
-if one of the included crystals has decent transparency, you might even try conoscopy between crossed polars under the microscope (check for optical axis under crossed polars, and then use the conoscope)
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Pierre Joubert
Joined: 09 Mar 2012
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Location: Western Cape
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Posted: Dec 12, 2014 12:06 Post subject: Re: Oddities from Brandberg, Namibia |
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cascaillou wrote: | Hi,
concerning the identity of those white crystals, you could try:
-LW and SW UV (if any fluorescence, report intensity and color of fluorescence, and also check in complete darkness if there's any residual phosphorescence once the UV have been cut)
-check the transparent ones for doubling of their inclusions/edges (with a good microscope)
-check for cleavages or any characteristic twinning under the microscope
-you could also try crossed polars under the microscope, checking for lamellar twining, if any.
-if one of the included crystals has decent transparency, you might even try conoscopy between crossed polars under the microscope (check for optical axis under crossed polars, and then use the conoscope) |
Hi Cascaillou. I have none of those items needed :-(
_________________ Pierre Joubert
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cascaillou
Joined: 27 Nov 2011
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Posted: Dec 12, 2014 12:14 Post subject: Re: Oddities from Brandberg, Namibia |
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Christmas is coming! :-)
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Pierre Joubert
Joined: 09 Mar 2012
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Location: Western Cape
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Posted: Dec 12, 2014 14:03 Post subject: Re: Oddities from Brandberg, Namibia |
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cascaillou wrote: | Christmas is coming! :-) |
Hi Cascaillou, shall I send you my postal address via PM? :-)
_________________ Pierre Joubert
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Pierre Joubert
Joined: 09 Mar 2012
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Posted: Jan 14, 2015 11:35 Post subject: Re: Oddities from Brandberg, Namibia |
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Hi Mike and Vic. I would like to continue our discussion on inverted crystals under this topic as the specimen comes from Tafelkop area, near Brandberg. Perhaps Peter, Duncan and other experts can chip in. As far as I know, 'inverted' crystals are hollow and formed slower than other gas inclusions. Sometimes these have water with an air bubble trapped inside.
Mineral: | Quartz |
Locality: | Brandberg area, Erongo Region, Namibia | |
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Dimensions: | 40 x 09 x 08 mm |
Description: |
Quartz with inverted crystals. |
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20530 Time(s) |
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Mineral: | Quartz |
Locality: | Brandberg area, Erongo Region, Namibia | |
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Dimensions: | 40 x 09 x 08 mm |
Description: |
Quartz with inverted crystals. Same as above. |
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20503 Time(s) |
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Mineral: | Quartz |
Locality: | Brandberg area, Erongo Region, Namibia | |
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Dimensions: | 40 x 09 x 08 mm |
Description: |
Quartz with inverted crystals. Same as above. |
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20496 Time(s) |
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Mineral: | Quartz |
Locality: | Brandberg area, Erongo Region, Namibia | |
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Dimensions: | 40 x 09 x 08 mm |
Description: |
Quartz with inverted crystals. Same as above. |
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20531 Time(s) |
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Mineral: | Quartz |
Locality: | Brandberg area, Erongo Region, Namibia | |
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Dimensions: | 40 x 09 x 08 mm |
Description: |
Quartz with inverted crystals. Same as above |
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20519 Time(s) |
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_________________ Pierre Joubert
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Michael Shaw
Site Admin
Joined: 30 Apr 2008
Posts: 2095
Location: Oklahoma
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Posted: Jan 14, 2015 15:11 Post subject: Re: Oddities from Brandberg, Namibia |
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Wonderful piece Pierre, and great photos.
Michael
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Don Lum
Joined: 03 Sep 2012
Posts: 2869
Location: Arkansas
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Posted: Jan 14, 2015 17:53 Post subject: Re: Oddities from Brandberg, Namibia |
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Pierre,
Great specimen and photographs.
Don
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