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Rhodochrosite

Posted by Rock Currier  
avatar Re: Rhodochrosite
April 27, 2009 10:55AM
    
Thx Rock, yw,

i noticed that this picture has been erroneously added twice: [www.mindat.org]

.. it should be deleted at the Louise mine Bürdenbach description, the specimen is from Oberneisen. I will try to get the Oberneisen description ready asap but may last a few days.

cheers
Roger
avatar Re: Rhodochrosite
April 27, 2009 08:55PM
Roger,
Woops! Must have happened during one of my late night 8 hour sessions when my eyeballs were getting square. Fixed. Much thanks.

Rock Currier
Crystals not pistols.
avatar Re: Rhodochrosite
April 29, 2009 11:24AM
The material from Durnford Quarry is largely rhodochrosite. I ran X-ray powder diffraction (XRD) and Energy dispersive X-ray analysis (EDX/EDS) on material from the original find (2007) and several XRD runs produced perfect matches with the patterns for rhodochrosite. Questions were raised over what the true manganese content was, so I ran the XRD powder by EDS on a an SEM stub in 2008 and it came back with the ratio 10.47-11.54% Mn: 1.38-1.70 % Ca: 0.46-0.55 % Mg: no detectable Fe. Obviously this is semi-quantitative as you cannot measure the carbonate component, but clearly it is manganese-dominant.

The locality was kept vague, due to issues regarding people collecting there without permission, but most of the new specimens sold during 2007/2008 as Merehead Quarry, are actually from Durnford Quarry. Merehead Quarry as noted earlier did produce pink samples, but most have turned out to be manganese-rich calcite.

Tom Cotterell
Amgueddfa Cymru - National Museum Wales

[www.mindat.org]
[www.mindat.org]

Ok the two pics are now loaded .... hope the pic. quality is good enough for you.

About the find .... one of my best collecting days in the UK !! Found memories ....
It was on March 24th 2007 during a Russell Society field trip, and i believe about 4/5 of us were lucky enough on the day. One week after there was not much left i heard and rest went probably to the crusher.

I would not count the find in flats, but would say about 15 - 20 of good/top quality were collected on the day (kept 4 and gave a few - sic !!). Some had also Wulfenite but not on the specimen i collected, but i believe the one uploaded was the largest Rhodo. cavity found.

Rock,
as mentionned by Ian it is a Limestone quarry but i am really not well placed to give more on exact geology .... hope someone else will help you here if needed.
Diifficult to comment also in details on the wulfenite as I have not seen all ... was certainly very rare and have not found one. But i know at least of one specimen with an orange crystal of about 8mm.

Rock Currier
Crystals not pistols.



Edited 3 time(s). Last edit at 04/30/2009 08:03PM by Rock Currier.
Re: Rhodochrosite
June 09, 2009 03:25AM
Great job, Rock!

Rob Woodside wrote:

"Any rhodo collector would give their eye teeth to have a rhodo collection with these photoed rhodos, even if they are not all the world's best."

I can confirm that... 21 of the 206 (+/-) specimens shown above are in my collection. Surprisingly,
many of what I would consider my better/best rhodos are -not- among those 21, including:

[www.foxcove.com]
One of the cleanest (on the exterior) Catamarca stalagtites I've ever seen:

[www.foxcove.com]
My nicest of this habit from N'Chwaning

[www.foxcove.com]
[www.foxcove.com]
[www.foxcove.com]
Another somewhat rare N'Chwaning habit... and another...

[www.foxcove.com]
[www.foxcove.com]
OK, so even though I can't afford the very best ones, these
are some of my best Sweet Home specimens

[www.foxcove.com]
Though small, still my favorite from Gabon

[www.foxcove.com]
[www.foxcove.com]
Some of my favorite Taxcos.

[www.foxcove.com]
[www.foxcove.com]
A couple of very unique Butte specimens

[www.foxcove.com]
Good for MSH!

[www.foxcove.com]
Probably better than anything you had above from the Eagle Mine

[www.foxcove.com]
Major Kazhaki action

[www.foxcove.com]
Another from Aggeneys, Broken Hill, SA (the other one
shown above is also in my collection)

[www.foxcove.com]
[www.foxcove.com]
[www.foxcove.com]
Some more good Uchhers

[www.foxcove.com]
Pale, yes, but cool cubic Pyrites...

[www.foxcove.com]
How bout Utah?

[www.foxcove.com]
[www.foxcove.com]
Japan

[www.foxcove.com]
Good St. Eulalia

[www.foxcove.com]
Wisconsin!

[www.foxcove.com]
Pasto Bueno

[www.foxcove.com]
Llallagua

Alas, there are more, but I'm out of time for the moment.

Rhodo Love to All smiling smiley,

- Richard
avatar Re: Rhodochrosite
June 09, 2009 05:18AM
[www.mindat.org]

[www.mindat.org]


available if needed....best, joe



Edited 1 time(s). Last edit at 06/09/2009 05:19AM by Joseph Freilich.
avatar Re: Rhodochrosite
June 09, 2009 06:57AM
"We need someone who know about Greek minerals to tell us about the specimens from this mine.
[Rock Currier, 2 January 2009]"


What exactly would you like to know? I have a house a few kilometeres away from the mines and my collection of Greek minerals has a special section devoted to rhodochrosite.

Firstly I'd like to let you know that rhodo rhombs also occur in this mine. I have one associated with lustrous bournonite. Would you like some additional pics?

Chris?



Edited 1 time(s). Last edit at 06/09/2009 06:58AM by Christos Spiromitros.
avatar Re: Rhodochrosite
June 09, 2009 10:17AM
Richard,
I would like to add many pictures in you list above to the article. How many of the pictures have been uploaded to Mindat? I checked a few of them and they did not appear to be in the mindat gallery. All the pictures that appear in the Best Minerals articles are drawn from the Mindat galleries. The fact that they are there means the uploader has given mindat permission to use them on the site and that eliminates copyright problems. If I would choose from your images above in your post, would you up load them to Mindat?

Rock Currier
Crystals not pistols.
avatar Re: Rhodochrosite
June 09, 2009 10:32AM
Christos,
Almost anything you could tell me is more than we now know. You might start with a little description of the mine and its geology and history and then tell us about the specimens it produces. Especially the rhodochrosites, but not necessarily limited to those, because we will probably use what you tell us in articles on the other minerals that were/are produced by the Cassandra Mine. Basically how long has the mine produced specimen, here specifically rhodochrosite, how many specimens has it produced? Is it still producing? What do you think of the specimens from there we have pictured? How good are they? Are there some types like the rhombs that we are missing? Yes, if you can upload a good picture of rhombs from the mine we would probably use it in the article. If you can supply pictures of better specimens that we now have pictured we would be glad to have those as well. When I make the selection of images for the articles I am writing, I rarely look to see who submitted the picture. I think that keeps the process as impartial as possible.

Rock Currier
Crystals not pistols.
avatar Re: Rhodochrosite
July 16, 2009 09:26PM
The following was provided by Jolyon Ralph July 14, 2009 12:47PM

Having visited the quarry last friday with a collector who was one of the original discoverers of the find, I can let you know a little more about this.

The original find was found in blackish manganese-rich boulders broken open after a recent blast. Many specimens were recovered that day but essentially all were from one boulder that was broken open. As was said before, there were probably only 10-15 top quality pieces, and number of lesser-quality.

The crystalline material associated with it has been reported as Manganite.

After this visit, people unknown broke into the quarry illegally (cutting a hole in the access fence to do so) to search for this material, and it is possible most of the specimens on the market are now this material (I am told most, if not all, of the specimens originally found in the first trip still remain with the collectors). Needless to say this activity causes great problems between collectors and quarry managers, and it is fortunate that there are still good relations between the operators of the Durnford quarry and collector groups.

On our trip last week there was little found (there has been no new blasting in the area since the 2007 blast - and no further blasting in the area is planned as the quarry is not currently expanding due to the economic climate). I found a couple of small pieces of massive rhodochrosite with nice colour, and one with some nice banding I have cut and partially polished to show the structure.

Rock Currier
Crystals not pistols.
avatar Re: Rhodochrosite
July 29, 2009 11:07PM
    
Rock,
i just added some pics (you know, the red green mafia) ... may be you can use them:

[www.mindat.org]
[www.mindat.org]
[www.mindat.org]

Some more pictures for Galena to come soon .. will post in the Galena thread,

cheers
Roger
avatar Re: Rhodochrosite
July 30, 2009 08:07PM
Roger,

Wow, that specimen from the Dr. Geier Mine knocked me out. Will certainly use two of them, perhaps all three. Thanks

Rock Currier
Crystals not pistols.
Re: Rhodochrosite
August 05, 2009 06:51PM
Re: Wolf Mine
Rhodochrosite specimens from Wolf Mine seem always to be a uniform orange color. Does anyone know the composition of these specimens that might explain the distinctly orange color? One suspects Iron, but Karen Weinrich has implicated higher iron levels with definite pink coloration. Any information?
Bill
avatar Re: Rhodochrosite
August 05, 2009 10:03PM
    
Bill,
no idea ... but the Wolf rhodos are far from being uniform in colour... my collection specimen has the slight orange tint you mentioned but i have seen many other specimens from brownish to intense pinkish. There are also slight salmon pink ones so there is no 'typical' colour but more a typical habit of the Wolfies smiling smiley

cheers
Roger

P.S. if i find analyses i will post
avatar Re: Rhodochrosite
December 13, 2009 08:15AM
    
Rhodochrosite on Sphalerite
Batantzi mine
Maden district
Bulgaria


avatar Re: Rhodochrosite
December 13, 2009 10:51AM
Trevor,
Thanks for the image. I have included it in the article. What can you tell us about the deposit in general and the rhodochrosite specimens that come from there. How many were found? When. Is it a base metal mine? Something of the history, geology?

Rock Currier
Crystals not pistols.
NH
Re: Rhodochrosite
December 14, 2009 12:36AM
Today's photo of the day from the Otra Estrella claim in Chihuahua, Mexico is very stunning (if small) and seems like it could have a place here. Unfortunately, there is not much information on the Mindat locality page.

Two photos:
© Enrico Bonacina
© Enrico Bonacina
avatar Re: Rhodochrosite
December 14, 2009 02:11AM
NH,
Its a beautiful little crystal and certainly a candidate. Why don't you see if you can find out from Bill Pangczer or some other knowledgeable person something about the mine and what kind of specimens it produces.

Rock Currier
Crystals not pistols.
avatar Re: Rhodochrosite
December 23, 2009 02:29AM
    
Rock,

As you requested, here is the wheat sheaf rhodo.

Rhodochrosite(wheat sheaf style) on Manganite
N'Chwaning Mine,
Kalahari Manganese Field
South Africa


avatar Re: Rhodochrosite
December 30, 2009 10:22AM
    
Hi Rock,

The Kara mines at Hampshire have provided some very interesting Rhodochrosite over the last few years. Nealy all went into local collections. The unusual crystal formation makes this minor occurrence quite important and the quality of the specimens are of high quality. The following comments are available for addition to BM.

Consider the following photos; Kara Mine, Hampshire, Tasmania - 274812, 272696, 272695, 272694, 121441,etc

Rhodochrosite from the Kara Mine at Hampshire Tasmania is an uncommon carbonate mineral, the dominant carbonate being calcite. It has been found in small amounts in various parts of the deposit mainly as small botryodal clusters with quartz veins. In 2005 it was noted close to the western contact of the underlying granite in late stage quartz, calcite veins (Sorrel Bottrill 2005). It was also noted as small cavities in the massive magnetite ore. The Rhodochrosite is considered “Calcic “(Mn75Ca25) and will often grade into manganoancalcite (Bottrill Baker2008). The Rhodochrosite appearance is light to median pink crystalline botryodal growths and prismatic crystals that have overgrown and intergrown manganoancalcite, often pseudomorphing kutnahorite; this habit is very similar to that noted at Broken Hill.


Ref –
Minerals of Kara Mine, Tasmania – Steve Sorrell, Ralph Bottrill (2005);
A Catalogue of the Minerals of Tasmania; Geo. Surv. Bull. 73 – R. S. Bottrill, W. E. Baker (2008)
avatar Re: Rhodochrosite
December 31, 2009 01:31PM
Andrew,

Excellent! Ill have to add all that to the article in the next day or two.

Rock Currier
Crystals not pistols.
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