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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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 Posted: Feb 16, 2014 11:23 Post subject: Calcite and Oyelite from N'Chwaning |
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I had some fun photographing a small, unusual calcite specimen from N' Chwaning and want to share a few photos.
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Calcite and oyelite
N'Chwaning Mines (KMF), Kuruman, Kalahari, South Africa
31 x 18 x 18 mm |
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12449 Time(s) |
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| Description: |
Calcite and oyelite
N'Chwaning Mines (KMF), Kuruman, Kalahari, South Africa
31 x 18 x 18 mm
Same as above |
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12470 Time(s) |
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| Description: |
Calcite and ?
N'Chwaning Mines (KMF), Kuruman, Kalahari, South Africa
F.O.V. approx. 11 mm |
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12441 Time(s) |
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Calcite
N'Chwaning Mines (KMF), Kuruman, Kalahari, South Africa
FOV approx. 6 mm
The calcite grew on another crystal, possibly calcite with some or other mineral coating. Note the small round minerals (or bubbles)? |
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12431 Time(s) |
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Oyelite
N'Chwaning Mines (KMF), Kuruman, Kalahari, South Africa
Field of view, approx. 1 mm
Not the best of photos or example of oyelite, but part of the specimen. |
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12434 Time(s) |
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| Description: |
Unknown mineral in calcite.
N'Chwaning Mines (KMF), Kuruman, Kalahari, South Africa
Field of view, approx. 2 mm |
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12451 Time(s) |
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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marvsT/Nminerals
Joined: 06 Nov 2008
Posts: 68
Location: Juda, Wisconsin
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| Posted: Feb 16, 2014 19:57 Post subject: Re: Cacite and oyelite from N'Chwaning |
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A beautiful and intriguing specimen, Pierre. I have been building a collection of minerals from the Kalahari Manganese Fields for several years and have never seen anything like your specimen anywhere. The first calcite I saw from one of the N'Chwaning mines was so clear I thought at first it was a quartz crystal. Thanks, Marv
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Great things can be found in small packages! |
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Cesar M. Salvan
Site Admin
Joined: 09 Jun 2008
Posts: 126
Location: Alcalá de Henares
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| Posted: Feb 16, 2014 20:13 Post subject: Re: Cacite and oyelite from N'Chwaning |
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Pierre,
I analyzed the "phantom" in the core of the calcite and I found SiO2, so I guess Marv is right :). The core is surrounded by bubbles, which could be product of reaction between carbonate and the silica. Anyway are interesting crystals.
I contribute with more pictures of a specimen courtesy of Pierre.
| Description: |
Oyelite
N'Chwaning I mine, Kuruman, Northern Cape, South Africa
Crystal 1 cm |
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12394 Time(s) |
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| Description: |
Calcite
N'Chwaning I mine, Kuruman, Northern Cape, South Africa
crystal 1 cm
Note the weird visual effect product of the optical properties of calcite. |
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12393 Time(s) |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Feb 17, 2014 02:55 Post subject: Re: Cacite and oyelite from N'Chwaning |
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| marvsT/Nminerals wrote: | | A beautiful and intriguing specimen, Pierre. I have been building a collection of minerals from the Kalahari Manganese Fields for several years and have never seen anything like your specimen anywhere. The first calcite I saw from one of the N'Chwaning mines was so clear I thought at first it was a quartz crystal. Thanks, Marv |
Hi Marv. I remember when I first saw these clear calcites at a friend, years ago, I was convinced they where quartz till he put some acid on one small piece to prove me wrong. They have a distinct waxy feeling.
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Feb 17, 2014 03:11 Post subject: Re: Cacite and oyelite from N'Chwaning |
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| Cesar M. Salvan wrote: | Pierre,
I analyzed the "phantom" in the core of the calcite and I found SiO2, so I guess Marv is right :). The core is surrounded by bubbles, which could be product of reaction between carbonate and the silica. Anyway are interesting crystals.
I contribute with more pictures of a specimen courtesy of Pierre. |
Hi Cesar. Those are really nice pictures. What camera equipment did you use? Thank you for the analyses. I studied the small specimen and found some of the interior coated crystals hollow (probably due to an overcoating of a mineral that has since dissolved). I must actually take a few more photos of two pieces in our collection, that has very distinct and weird examples of what I mentioned. P1040736.JPG and P1040746.JPG
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Cesar M. Salvan
Site Admin
Joined: 09 Jun 2008
Posts: 126
Location: Alcalá de Henares
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| Posted: Feb 17, 2014 05:02 Post subject: Re: Cacite and oyelite from N'Chwaning |
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Hi Pierre,
I use a Nikon Coolpix camera attached to a Zeiss Discovery microscope. I'm a microscopist and the Discovery is my workhorse :)
Send me the weird specimens and I'll analyze them.
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Feb 17, 2014 06:42 Post subject: Re: Cacite and oyelite from N'Chwaning |
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| Cesar M. Salvan wrote: | Hi Pierre,
I use a Nikon Coolpix camera attached to a Zeiss Discovery microscope. I'm a microscopist and the Discovery is my workhorse :)
Send me the weird specimens and I'll analyze them. |
Hi Cesar. No wonder your photos look so cool! I will certainly remember your offer as I occasionaly encounter some very unusual inclusions. Thank you for your kind gesture.
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Debbie Woolf
Joined: 09 Feb 2009
Posts: 168
Location: Kent
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| Posted: Feb 22, 2014 10:06 Post subject: Re: Cacite and Oyelite from N'Chwaning |
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| Nice discussion, some N'Chwaning calcite's are so under-rated.
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Feb 22, 2014 11:39 Post subject: Re: Calcite and Oyelite from N'Chwaning |
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| Debbie Woolf wrote: | | Nice discussion, some N'Chwaning calcite's are so under-rated. |
Hi Debbie. Good to hear from you again. This year has been much to busy for my liking. As soon as I get some quality time, I want to take a few more photos of N'Chwaning calcites. There are some strange growth patterns that needs to be clarified and I do not have that knowledge. Best regards.
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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Don Lum
Joined: 03 Sep 2012
Posts: 2856
Location: Arkansas
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| Posted: Feb 22, 2014 11:47 Post subject: Re: Calcite and Oyelite from N'Chwaning |
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Pierre,
That is a fascinating specimen with the "negative crystals."
Don
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Pierre Joubert
Joined: 09 Mar 2012
Posts: 1605
Location: Western Cape
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| Posted: Feb 22, 2014 12:03 Post subject: Re: Calcite and Oyelite from N'Chwaning |
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| Don Lum wrote: | Pierre,
That is a fascinating specimen with the "negative crystals."
Don |
Hi Don. I suppose you may have a point calling them 'negative 'crystals. It is indeed very interesting specimens.
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Pierre Joubert
'The tree of silence bears the fruit of peace. ' |
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