We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences


Spanish message board






Newest topics and users posts
08 Jul-11:45:34 Re: new technology for crystal models (Bob Morgan)
08 Jul-09:47:41 Re: new technology for crystal models (Bob Carnein)
08 Jul-08:32:41 Re: collection of michael shaw (Michael Shaw)
07 Jul-17:55:33 Re: new technology for crystal models (Josele)
07 Jul-17:42:46 Re: collection of sante celiberti - a mineralogical trip through italy (Firmo Espinar)
07 Jul-16:22:42 Re: collection of sante celiberti - a mineralogical trip through italy (Sante Celiberti)
07 Jul-16:19:22 New technology for crystal models (Bob Carnein)
07 Jul-13:51:12 Popular minerals - laurentthomasite (Jordi Fabre)
07 Jul-13:40:22 Re: don lum collection (Don Lum)
07 Jul-11:08:49 Re: collection of volkmar stingl (Volkmar Stingl)
07 Jul-10:55:27 Re: collection of volkmar stingl (Volkmar Stingl)
07 Jul-09:40:41 Re: collection of firmo espinar (Firmo Espinar)
06 Jul-16:03:50 Re: collection of sante celiberti - a mineralogical trip through italy (Sante Celiberti)
06 Jul-14:02:46 Re: tourmaline? ural mountains? (Peter)
06 Jul-08:16:02 Re: tourmaline (Jordi Fabre)
06 Jul-07:30:08 Re: tourmaline (Bob Morgan)
06 Jul-01:05:33 Re: tourmaline (Peter Lemkin)
05 Jul-19:44:20 Re: tourmaline (Josele)
05 Jul-16:14:43 Re: tourmaline (Roger Warin)
05 Jul-16:12:10 Re: tourmaline (Bob Carnein)
05 Jul-16:00:27 Re: collection of sante celiberti - a mineralogical trip through italy (Sante Celiberti)
05 Jul-15:53:10 Re: tourmaline (Bob Morgan)
05 Jul-09:04:13 Re: tourmaline (Josele)
05 Jul-07:34:32 Re: tourmaline (Roger Warin)
05 Jul-06:45:51 Re: tourmaline (Mathias)

For lists of newest topics and postings click here


RSS RSS

View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  

Like
69960


The time now is Jul 09, 2020 06:06

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
Calcite Forms - (4)
  Goto page Previous  1, 2, 3, 4, 5, 6, 7, 8, 9  Next
  Index -> Featured Columns of FMF
Like
37


View previous topic :: View next topic  
Author Message

alex chaus




Joined: 05 Sep 2011
Posts: 22
Location: FSU


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Oct 28, 2012 21:08    Post subject: Re: Calcite Forms - (4)  

Hi, all.
Some contribution to calcite theme from Kyrgyzstan. All images provided are from the same location - Tereksay stibnite mine, collected at different levels during 80th to 2000 years. rusty film on some crystals is iron oxide hard to remove (any advise how to?). Sorry for images bad quality they are just from my catalog.
Alex



01046.JPG
 Description:
Calcite twin
Tereksay mine
5 by 3 cm
 Viewed:  24932 Time(s)

01046.JPG



01431.JPG
 Description:
Calcite on quartz plates
Tereksay mine
big crystal about 3 by 3 cm, specimen about 20 by 20 cm
 Viewed:  25005 Time(s)

01431.JPG



00952.JPG
 Description:
Calcite (complicated shape)
Tereksay mine
13 by 15 cm
 Viewed:  24966 Time(s)

00952.JPG


Back to top
Reply to topic Reply with quote
Like
   

GneissWare




Joined: 07 Mar 2008
Posts: 1284
Location: California


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Oct 28, 2012 21:29    Post subject: Re: Calcite Forms - (4)  

alex chaus wrote:
Hi, all.
rusty film on some crystals is iron oxide hard to remove (any advise how to?).
Alex


Hi Alex,
In some parts of the world you can get Super Iron Out (google Super Iron Out MSDS for the chemistry). It is a buffered mix of Sodium hydrosulfite and Sodium metabisulfite. You can try it on a sample to make sure it doesn't etch the Calcite.
Bob
Back to top
Reply to topic Reply with quote
Like
   

alex chaus




Joined: 05 Sep 2011
Posts: 22
Location: FSU


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Oct 28, 2012 23:51    Post subject: Re: Calcite Forms - (4)  

Thank you, Bob, I'll try to find or get it from somewhere abroad.
Alex
Back to top
Reply to topic Reply with quote
Like
   

Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Nov 29, 2012 17:31    Post subject: Re: Calcite Forms - (4)  

The "Calcite (complicated shape) Tereksay mine" specimen is very interesting!

Below is a neat specimen I've been trying to photograph. It has copper inclusions just under the surface which sparkle in the light, no luck showing that here yet. Some of the inclusions stick out of the faces. This is from Hancock, MI.

Cheers,
Elise



CalciteCu_0132sm.jpg
 Description:
Calcite included with Copper
Hancock, MI
10 x 8 x 5 cm
 Viewed:  24810 Time(s)

CalciteCu_0132sm.jpg



_________________
Elise Skalwold
Back to top
Reply to topic Reply with quote
Like
   

Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Nov 29, 2012 17:46    Post subject: Re: Calcite Forms - (4)  

and one more - I was trying to capture the curved growth features on the crystal faces; turned into blow-out areas, but more or less shows it. This is from Sweetwater Mine, MO. The calcite is on galena, but the latter is not visible in this view.

Elise



calcite_152_sm.jpg
 Description:
Calcite on Galena
Sweetwater Mine, MO
7 x 4,5 x 2 cm
 Viewed:  24772 Time(s)

calcite_152_sm.jpg



calcite_94sm.jpg
 Description:
Calcite on Galena
Sweetwater Mine, MO
7 x 4,5 x 2 cm
 Viewed:  24709 Time(s)

calcite_94sm.jpg


Back to top
Reply to topic Reply with quote
Like
   

am mizunaka




Joined: 09 Apr 2010
Posts: 1394
Location: California


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Mar 04, 2013 03:32    Post subject: Re: Calcite Forms - (4)  

Quartz mostly replacing calcite. The backside has a few small areas of calcite visible.
A higher resolution version is here: https://www.mindat.org/xpic.php?fname=0269344001362379359.jpg



DalQtzCalcite1.jpg
 Description:
Quartz after Calcite
Dal'negorsk, Primorskiy Kray, Far-Eastern Region, Russia
10.7 x 8.4 cm
 Viewed:  24089 Time(s)

DalQtzCalcite1.jpg


Back to top
Reply to topic Reply with quote
Like
   

Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 28, 2013 18:19    Post subject: Re: Calcite Forms - (4)  

Hi,

This is an old specimen, badly worn. The label indicates it is a twin. I was wondering how it grew - there doesn't seem to be a point of attachment, though one end and a side seems to have a reentrant angle and a seam respectively - I think that shows in the photo where I am holding it. Just thought it is neat.

Cheers
Elise



calcite38aWsm.jpg
 Description:
Calcite twin
Rossie, New York, USA
50 x 50 x 35 mm
Old specimen, badly abraded.
 Viewed:  23629 Time(s)

calcite38aWsm.jpg



calcite40aWsm.jpg
 Description:
Calcite twin
Rossie, New York, USA
50 x 50 x 35 mm
Old specimen, badly abraded.
 Viewed:  23709 Time(s)

calcite40aWsm.jpg


Back to top
Reply to topic Reply with quote
Like
   

Don Lum




Joined: 03 Sep 2012
Posts: 2315
Location: Arkansas


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 28, 2013 18:34    Post subject: Re: Calcite Forms - (4)  

IT IS NEAT!!
_________________
hogwild
Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 688
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 28, 2013 20:11    Post subject: Re: Calcite Forms - (4)  

Elise wrote:
Hi,

This is an old specimen, badly worn. The label indicates it is a twin. I was wondering how it grew - there doesn't seem to be a point of attachment, though one end and a side seems to have a reentrant angle and a seam respectively - I think that shows in the photo where I am holding it. Just thought it is neat.

Cheers
Elise


It IS neat! This is the cleavage rhomb {10.1} (though a crystal form, not a cleavage) twinned on (00.1). How else can you get a di-trigonal pyramid in calcite?!!

I also have one from Rossie, New York, and a number of smaller ones from Long Lake. They appear to have grown attached by one of the edges of the triangle, which allows them to break off very easily while leaving minimal evidence of the attachment.

On mine, if I am interpreting them correctly, the only difference between the original faces of the twin and the cleavage surface where it broke away from the matrix is a higher luster and perhaps a more irregular surface on the breakage plane.

It would be wonderful to have some drawings of these crystals in place.

Moving the topic a bit, I understand that the wonderful "axe head" {10.1} twins from Egremont, Cumbria, England were developed within a field of small delicate prismatic untwinned crystals, with the pointed bases of the twins down, and one could go along and pop them off like picking cherries or lollipops. Perhaps this is crystallographic fantasy, but if true, I just wish I had been there!

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   

Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 29, 2013 10:34    Post subject: Re: Calcite Forms - (4)  

Hi Pete!

I took some more photos this morning to show the side that I thought might be the attachment and reentrant angle. It was at the top of the first image along with right-hand side. The specimen is nearly symmetrical. Is this something you can diagram with software? It would be neat to see a photo of the crystals on matrix, but I think I can imagine what you are describing. "Neat" is becoming a technical term.

Cheers,
Elise



calcite18aWsm.jpg
 Description:
Calcite Twin Rossie, New York, USA
50 x 50 x 35 mm
Old specimen, badly abraded.
 Viewed:  23547 Time(s)

calcite18aWsm.jpg



calcite26aWsm.jpg
 Description:
Calcite Twin Rossie, New York, USA
50 x 50 x 35 mm
Old specimen, badly abraded.
 Viewed:  23547 Time(s)

calcite26aWsm.jpg



_________________
Elise Skalwold
Back to top
Reply to topic Reply with quote
Like
   

Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 29, 2013 10:39    Post subject: Re: Calcite Forms - (4)  

This is another "neat" calcite specimen (in need of repair and creative conserving - see https://www.mineral-forum.com/message-board/viewtopic.php?p=31742#31742).


calcite07aWsm.jpg
 Description:
Calcite on Marcasite
Marsden's Diggings, Galena, Illinois
75 x 40 x 35 mm
 Viewed:  23551 Time(s)

calcite07aWsm.jpg


Back to top
Reply to topic Reply with quote
Like
   

Ru Smith




Joined: 13 Oct 2012
Posts: 362


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 29, 2013 21:16    Post subject: Re: Calcite Forms - (4)  

Pete Richards wrote:
...Moving the topic a bit, I understand that the wonderful "axe head" {10.1} twins from Egremont, Cumbria, England were developed within a field of small delicate prismatic untwinned crystals, with the pointed bases of the twins down, and one could go along and pop them off like picking cherries or lollipops. Perhaps this is crystallographic fantasy, but if true, I just wish I had been there!

Do you remember where you read that, Pete? Do you have a copy of the original text?
Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 688
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 30, 2013 08:01    Post subject: Re: Calcite Forms - (4)  

Ru Smith wrote:
Pete Richards wrote:
...Moving the topic a bit, I understand that the wonderful "axe head" {10.1} twins from Egremont, Cumbria, England were developed within a field of small delicate prismatic untwinned crystals, with the pointed bases of the twins down, and one could go along and pop them off like picking cherries or lollipops. Perhaps this is crystallographic fantasy, but if true, I just wish I had been there!

Do you remember where you read that, Pete? Do you have a copy of the original text?

Well, it is perhaps a case of partly having read it and partly my inference. In the ExtraLapis English edition on calcite, issue #4 (2003), in an article on Cumbrian calcite twins, Mick Cooper writes about calcites from West Cumbria and the Furness District, "In some cases these minerals were so loosely attached to the matrix that the miners could pluck the crystals from crystal-lined nests with their bare hands." And elsewhere, "...the chunkier heart twin ... is generally found alone with barely a mark to show where it had been attached to the matrix". This is true of my three examples, and it certainly would have been easy to snap them off. All three have small prismatic crystals at the base, apparently engulfed as the twins grew, though I cannot document having read this anywhere.

Note the problem with giving descriptive names to twins - I apparently used the wrong name. Cooper also mentions "axe head" twins, but in his usage these are thinner and more delicate.

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 688
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 30, 2013 08:46    Post subject: Re: Calcite Forms - (4)  

Elise wrote:
Hi Pete!

...Is this something you can diagram with software?...

Cheers,
Elise


Below is a diagram of the crystal you showed. Top row is looking at the crystals from the side in standard crystallographic orientation, bottom row is looking at them down the c axis. The sequence shows first the difference between twinned and untwinned crystals and then the minor distortions of ideal geometric twinned shape that produce a crystal much like yours. To use a technical term, neat!



calcite twin.jpg
 Description:
 Viewed:  23408 Time(s)

calcite twin.jpg



_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   

Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 31, 2013 09:25    Post subject: Re: Calcite Forms - (4)  

Hi Pete,

I wasn't able to find anything like this in a text, so I am very excited to see this diagrammatic explanation - thank you!

Is this a rare type of twinning or is this an unusual manifestation of a common type of twinning?

The lower drawing on the right side showing only one notch apparently matches this specimen. I assume the "seam" along the edge is a reentrant angle. Originally, I thought it was only along the edge shown above, but there seems to be a less obvious one along the adjacent edge terminating at the same battered point/notch.

The other edge shows a very slight line of luster difference (the bottom edge in the first image above), but I would be hard-pressed to capture it in a photograph. Perhaps that is cleavage from breaking off attachment to matrix.

There are no notes with the specimen other than a minimal label. I thought that the patina might indicate that it had been kicking around the dept for decades or even a century, but morning coffee debate team wasn't convinced. I think it would be nice to display with a diagram and photos to show the different views as it does not look as impressive just sitting on a shelf ....although when I pulled it out of a storage drawer it made my day (along with the ice cream cone above)! It will be a very nice addition to the museum.

Cheers,
Elise
Pete Richards wrote:
Below is a diagram of the crystal you showed. Top row is looking at the crystals from the side in standard crystallographic orientation, bottom row is looking at them down the c axis. The sequence shows first the difference between twinned and untwinned crystals and then the minor distortions of ideal geometric twinned shape that produce a crystal much like yours. To use a technical term, neat!

_________________
Elise Skalwold
Back to top
Reply to topic Reply with quote
Like
   

Ru Smith




Joined: 13 Oct 2012
Posts: 362


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 31, 2013 15:33    Post subject: Re: Calcite Forms - (4)  

In https://www.mineral-forum.com/message-board/viewtopic.php?p=31768#31768 Pete Richards wrote:
Well, it is perhaps a case of partly having read it and partly my inference. In the ExtraLapis English edition on calcite, issue #4 (2003), in an article on Cumbrian calcite twins, Mick Cooper writes about calcites from West Cumbria and the Furness District, "In some cases these minerals were so loosely attached to the matrix that the miners could pluck the crystals from crystal-lined nests with their bare hands." And elsewhere, "...the chunkier heart twin ... is generally found alone with barely a mark to show where it had been attached to the matrix". This is true of my three examples, and it certainly would have been easy to snap them off. All three have small prismatic crystals at the base, apparently engulfed as the twins grew, though I cannot document having read this anywhere.

Many thanks Pete, I'd not read that. It is a wonderful image - a garden of calcite twins ready to be plucked.
Back to top
Reply to topic Reply with quote
Like
   

GneissWare




Joined: 07 Mar 2008
Posts: 1284
Location: California


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 18, 2013 09:17    Post subject: Re: Calcite Forms - (4)  

A few more Calcites to ponder...


FJB5972a.jpg
 Description:
Calcite
Flambeau Mine, near Ladysmith, Rusk County, Wisconsin, USA
81 x 69 x 43 mm

From the East End Footwall Orebody, Marker 418.0 1010 Level

"Wheat sheave" shaped white Calcites to 32 x 16 mm, with pearly luster and light-red Hematite accents are perched on sparkly contrasting matrix of Calcite. Although there is some damage, this is a very rare and important specimen-one of only three Calcites found at the Flambeau Mine in Wisconsin, and the very best one found. It was collected by Casey Jones who sold it to F. John Barlow (#5972), and was later consigned to Casey upon dissolution of the Barlow collection.
 Viewed:  22693 Time(s)

FJB5972a.jpg



FJB5972b.jpg
 Description:
Calcite
Flambeau Mine, near Ladysmith, Rusk County, Wisconsin, USA
81 x 69 x 43 mm

Another view.

I don't know the correct name for this habit, hence the "wheat sheave" reference.
 Viewed:  22670 Time(s)

FJB5972b.jpg



IMG_6107.jpg
 Description:
Calcite
Hercules Mine, Municipio de Camargo, Coahuila, Mexico
191 x 87 x 65 mm

This cluster of Calcite crystals consists of both elongated scalenahedrons and butterfly twins (to 44 mm) with a reddish tinge from Hematite inclusions that deepens in color towards the centers of the Calcite crystals forming nice Hematite phantoms. The Calcites also display distinct chatoyancy. Although it presents damage around the margins where it was removed, it is one of the only surviving specimens from what was reportedly a large, several meters long cave completely covered by such Calcite. It was given to me by Francisco Aguilera who worked at the Hercules Mine and actually collected it. Casey Jones and I met Francisco through the mine office because he spoke some English.
 Viewed:  22706 Time(s)

IMG_6107.jpg



IMG_6110.jpg
 Description:
Calcite
Hercules Mine, Municipio de Camargo, Coahuila, Mexico
191 x 87 x 65 mm

Close up of the twins
 Viewed:  22689 Time(s)

IMG_6110.jpg



RG1007.jpg
 Description:
Calcite
Fuzichong Mine, Cenxi Co., Wuzhou Prefecture, Guangxi Zhuang A.R., China
99 x 85 x 44 mm

A very aesthetic poker-chip Calcite crystal, measuring 47 x 36 x 26 mm, showing a clear core and sharply-defined white caps is perched on contrasting matrix richly covered on both sides by gemmy, flattened Calcites to 8 mm. These Calcite crystals appear pseudo hexagonal, but are actually flattened rhombohedrons stacked on top of one another. This beautiful specimen shows nice color and contrast. A very aesthetic and unique specimen with no damage.
 Viewed:  22696 Time(s)

RG1007.jpg


Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 688
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 18, 2013 09:55    Post subject: Re: Calcite Forms - (4)  

Re the curved calcites from Flambeau, I tend to call them "potato chip habit"....

Re the twins from Mexico, they appear to be twins on {02-21} (relative to the morphological cell), which is probably the rarest of the four twin types of calcite. Neat specimen!

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   

GneissWare




Joined: 07 Mar 2008
Posts: 1284
Location: California


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 18, 2013 10:14    Post subject: Re: Calcite Forms - (4)  

Pete Richards wrote:
Re the curved calcites from Flambeau, I tend to call them "potato chip habit"....

I hadn't thought of that as a description, but like it! Essentially these are also stackd flattened rhombohedrons, but offset and twisted? I wonder why.

Pete Richards wrote:
Re the twins from Mexico, they appear to be twins on {02-21} (relative to the morphological cell), which is probably the rarest of the four twin types of calcite. Neat specimen!

I looked up this twin and that seems correct. Thanks for the info!
Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 688
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jul 18, 2013 12:50    Post subject: Re: Calcite Forms - (4)  

GneissWare wrote:
Pete Richards wrote:
Re the curved calcites from Flambeau, I tend to call them "potato chip habit"....

I hadn't thought of that as a description, but like it! Essentially these are also stackd flattened rhombohedrons, but offset and twisted? I wonder why.


I've never seen an explanation, but of course this is the same thing dolomite often does. Cleavages demonstrate that the lattice itself is twisted. It's tempting to think of an impurity that is a little too large or too small causing the strain, but that's just a guess. The distortion is quite systematic - the pointed outer part of each rhombohedral face is bent down (or in the case of the bottom faces, up).

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> Featured Columns of FMF   All times are GMT - 5 Hours
Page 6 of 9
  Goto page Previous  1, 2, 3, 4, 5, 6, 7, 8, 9  Next  

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


All pictures, text, design © Forum FMF 2006-2020


Powered by FMF