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Pseudomorphs & Replacements A & B

Posted by Rock Currier  
Keith Harshbarger
Re: Pseudomorphs A to C
April 16, 2011 04:44AM
Rock
Don't know if this is what you are looking for?

GLENDONITES
The large group of Worldwide Calcite pseudos, NOW known as "Glendonites", have been described under a variety of different individual names, as will as being assigned various parentage. Many were consolidated under the name "Pseudogaylussite"(Von Calker 1897). However E. S. Dana(1884) while studing similar Calcite pseudos from Nevada, believed the precursor would be a mineral yet to be discovered. That material was finally located in a Greenland Fjord(Pauly 1963). It proved to be a thermally unstable, Calcium carbonate hexahedrite. He named it Ikaite, after the fjord. As it was a massive mineral, it did not create much interest among pseudo collectors, except in Russia(Kaplin 1978). The first Ikaite crystals were found in drill cores, extracted of the Bransfield Strait, Antartica. At tenperatures above 4-5 degrees Celsius, the Ikaite separated into a "Mush" of tint Calcite crystals and water. Suess(1982), on the basis of crystal shape and the alteration to Calcite, declared Ikaite to be the missing precusor for this group of pseudomorphs. He refered to the pseudos as being "Glendonites", a term being used for specimens of this type from nearby Australia.
avatar Re: Pseudomorphs A to C
April 16, 2011 09:35AM
Hi Rock and all,

The article is going well I see.
Interesting stuff.

There is just a little error in the Chalcosite after wood from Clay Co. Texas. The name written is Chalcosie.
I also saw that the Ankerite after Calcite from Sainte Marie that I submitted, is missing.
With all the work you have it must have slipped thru the canvas.
Nothing personal if you dont include it.
I hope this helps.

Take care and best regards.

Paul.
avatar Re: Pseudomorphs A to C
April 17, 2011 10:17PM
Kieth, That is exactly the kind of stuff I am looking for. I wonder if I might tempt you to add a second paragraph bases on your own extensive experience about, where the best glendonites come from and how big they get and how many of them there out there and why we don't see many of them offered for sale etc. Could you add some comments about the double pseudomorphs of opal after calcite after Ikaite. We don't have a specific section on glendonites in the pseudomorph articles but show them under Calcite after Ikaite. I was thinking I might use what you write about them and place it in two places. Once in the lead in commentary about Calcite after Ikaite and also in the section after the Quartz, var. opal after Calcite after Ikaite from Australia.

I have taken a bit of a break from the Pseudomorph articles here on mindat. I have discovered that there were a whole slew of good pseudomorphs in our galleries by searching on the keywords replacing and replaced and altered and altering and I must now also integrate them into the articles which will require a lot of time. I have also gotten side tracked by trying to photoshop all my various locality images taken during my 30 or so years traveling around here and there. There are still thousands left to photoshop and it will probably take me another couple of weeks to get that done. Then there will be the task of uploading those to mindat. Jordi Fabre wanted some pictures to add to his translation of that bit I did about mineral collecting and then I thought I should post that as an article here on mindat and add a bunch of locality pictures to it and that got me trapped in my current obsession to finish the photoshopping of my locality pictures. But when I finish those, Ill get back and start hammering away at the pseudomorph articles again.

I was hoping I could get you interested enough to help and perhaps even take over the construction of what has become a much bigger job than I thought it would be about pseudomorphs. You know more about pseudomorphs than anyone I know and would be the ideal person to do this.

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
April 17, 2011 10:32PM
Paul,
Thanks for the correction on the Chalcocite error. You only found one error? I must be getting better as I get older or you are getting worse certainly you can do better than that!

I have added the Ankerite after calcite. Can you tell us how many of these were found and roughly when. Only from one mine? Is the one you posted about at good as they get?

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
April 19, 2011 08:51AM
Hi Rock,

Thanks for the reply.

I wrote a comment on the first page of this topic. That's all I have for the moment.
When I will have more time, I will dig all my information up and add it here.

I hope this helps.

Take care and best regards.

Paul.
avatar Re: Pseudomorphs A to C
April 20, 2011 09:29PM
Paul, When you say you wrote a comment on the first page of this topic, could you give me the URL of that page?

Rock Currier
Crystals not pistols.
avatar Re: Pseudomorphs A to C
April 21, 2011 02:51PM
Hi Rock,

Made a copy of what I wrote.


It is deffinately ankerite after calcite. Many test where done on these and the more recent by Fluck and Bari in 1982 and later on.
These are well known in the district since centuries. They are part of the " paragenèse à carbonates nobles " ( nobel carbonates paragenesis ) which is the paragenesis of the veins. The native silver and silver minerals from the district were always found near these pockets and IN this paragenesis.
At the museum at Ste Marie there is(was ?) a chalcopyrite crystal cluster with these doubly terminated pseudo's to 6 cm cris-cross over them. I saw that piece back in 78 and still dreaming about it.

What I find interesting about these pseudo's is that the original form of calcite ( the scalenohedron ) nearly completely dissapeared from the district except from 2 mines ( according to my observations of the specimens in many local collections and books on the district ). All the other calcite who was formed later, is from the " joplin" type or simple rhombs. The scalenohedron is observed in the Toussaint mine and in the Glück auf ( see my gallery ). I saw in 1987 in a local collection such a double terminatated pseudo af ankerite after calcite on matrix sparkled with very tiny gemmy double terminated joplin calcites. Just amazing. The collection has been dispersed whem the owner passed away in that same year. No idea where the specimen went. It would be great to find that piece back and take a pic of it and post it on Mindat.

I hope this helps.

Take care and best regards.

Paul.
avatar Re: Pseudomorphs A to C
April 22, 2011 01:24AM
Paul,
That is exactly what I was looking for. I have tweaked the English a bit and placed it in the article under the pictures of Ankerite after Calcite from France with your name and the year you wrote it, (this year) at the bottom. You should read it over and make sure I have not changed anything important.

Rock Currier
Crystals not pistols.
Re: Pseudomorphs A to C
April 22, 2011 03:24AM
us    
Rock, when you get back to this article there are a few misspellings I noted

Analc[ite] after Analcime and Siderite

Bavenite afer Beryl

Baventet after Beryl

In the paragraph after Calcite after Glauberite
"have been artificially died"

In the description of Carmenite after Balydonite
"1 mm balls or Carmenite"

Blame it on the editor in me.

Easy Goin'
USA



Edited 1 time(s). Last edit at 04/22/2011 03:25AM by Ed Godsey.
avatar Re: Pseudomorphs A to C
April 22, 2011 09:09PM
Ed,
Thank heaven someone is reading this stuff with a critical eye. Thanks for the corrections. They have been made. How would you like to take a crack at a best mineral article. If so, I would suggest something not to ambitious to start with, or perhaps one of the minerals like quartz, calcite, gypsum or fluorite from a single country? If so, let me know and Ill help you get started.

Rock Currier
Crystals not pistols.
Keith Harshbarger
Re: Pseudomorphs A to C
May 30, 2011 05:30AM
Rock
Will expand the info on Calcite pseudo Ikaite. Can also include notes on several of the photos, as many of the pseudos had individual nanes.The specimens labled as being after Gaylussite, can be left in place. Just note that they have now been reclassified as being after Ikaite. Did not find new photos of Calcite after Gaylussite posted.

I concocted a skeletal outline of a Pseudomorphic Classification, to including: Molds & Casts, Incrustations(Epimorphs etc.), Substitution,
Structural Alterations(Paramorphs) Hybrid Structural Pseudos(Uralite, Metamict & Exsolution Types) Chemicall Alteration(By Loss, by Gain &
Partial Exchange of componants). How detailed do you want the explainations to be?
Keith
avatar Re: Pseudomorphs A to C
May 30, 2011 11:46AM
Kieth,
To be honest, I don't know how detailed it should be. How much of what you have in mind for a detailed description has been written about before? How much will the casual reader of these articles be able to absorb? How much will the person who is interested seriously in pseudomorphs be able to absorb? I suspect that only the feed back by the people who use these articles will be able to eventually tell us these things. Keep in mind that whatever we do here may eventually be subsumed into some sort of database that can be searched in different ways to discover relationships that we are not yet aware. I suggest you write something as detailed as you can stand and if we ultimately discover it is too complex it could stand as a separate article and parts of it can be used in the introductory section for the pseudomorph articles with links that people can click on to take them to the main article or parts of the article that they are interested in. You might pick one type of pseudomorph for a detailed treatment and we can load it up here and request comments from the mindat community about if it should be simplified or not and that may give us a direction about which way to proceed.

I don't think there were any new pictures of Gaylussite after Calcite posted in the pseudomorph article and it is not clear from you post if you saw the currently posted ones, but they are in the calcite section of the Pseudomorphs A to C. If you agree that they are after Ikaite, I think it best that the captions should be changed so that they are shown as Calcite after Ikaite with an explanation below the pictures that they, as others of this kind were commonly described as Calcite after Gaylussite or Glauberite etc.


What ever notes you would care to add to the various images of pseudomorphs would be welcome, and Ill see that they are inserted below the appropriate images with a credit to you.

Rock Currier
Crystals not pistols.
Re: Pseudomorphs & Replacements A & B
February 17, 2013 12:24PM
Here is one of my many pseudomorphs of quartz (amethyst) afterr calcite

[www.mindat.org]
avatar Re: Pseudomorphs & Replacements A & B
July 14, 2013 09:18PM
Here are some notes about pseudomorphs made recently by Kieth Harshbarger that need to be incorporated into the article.

CHEMICAL ALTERATIONS

After a mineral is formed, the conditions of its formation will often change. The new conditions may cause the crystal to become unstable and separate into its component parts, and cause a different mineral to form. Sometimes new solutions may alter the host crystal without a change in its original form to create a new mineral that retains the shape of the old crystal. This alteration usually starts on the exterior of the crystal and slowly progresses inward. A few minerals seem to have a structural weakness along the axis of the elongation causing the alterations to start from the center outward. One thing to remember, is that this alteration process may not be carried to completion because of lack of enough new ingredients. Another reason for incomplete mineralization may be that the new mineral may form such a dense layer that ingredients causing the change may not be able to get to the unaltered part of the crystal. In some cases the conditions causing the change may change again which could include erosion processes or someone mining the deposit the crystal was in before the change could go to completion. A core of unaltered material may remain unseen within the pseudomorph.

Rome De Llsle (Crystallographie 1783) noted the change of blue (azurite) and red(cuprite) copper into green(malachite) and also the alteration of pyrite and siderite into iron oxides (limonite). He believed this alteration was similar to that which created petrified wood. Hauy (Tableau Comparatif 1809, 263) noted the same change and coined the term “Epigenis” for chemical alterations.

The various chemical alterations have been grouped by the major results of the process.

Alterations through the loss of a major component.

· Cuprite is reduced to native Copper through the loss of oxygen. Bisbee 102700

· Azurite loses carbonation and is reduced to native Copper. NM 246612


Alterations through the gain of a major component.

· Pyrrhotine gains a little Sulfer and alters to Pyrite. Freiberg 305309

· Magnetite gains Oxygen and alters to Hematite. Argentina 3967

· Cuprite becomes carbonated and alters to Malachite. Chessy 236395


Alterations in water of crystalizations.

· Borax loses 5 waters and alters to tincalconite. Boron 237307

· Inyoite loses 6 waters and alters to a granular meyerhofferite. 237204

· Anhydrite adds 2 waters and alters to Gypsum. If carried to completion a gain of volume may obscure the shape of the original crystal.


Alteration by partial exchange.

· The common goethite/limonite after pyrite presents the best example of this type. In the zone of weathering the sulfur in pyrite is lost and the iron oxidizes with the addition of oxygen to form this common type of pseudomorph. Spain 42802

· Orthoclase hydrates in the zone of weathering and also loses potassium and some silica to form pseudomorphs of kaolinite. Some of this silica may form quartz and remain at the site of the reaction to harden the pseudomorph. England 302068

· If a collector has only one pseudomorph in their collection it probably will be a Malachite after Azurite. This alteration results in a small change in the hydration and a small loss of carbonation. This often starts with solution moving from the matrix up through the center of the crystal. Green malachite sunburst often penetrate to the exterior of the blue crystal. Moroco 310735

Rock Currier
Crystals not pistols.



Edited 3 time(s). Last edit at 07/15/2013 12:12AM by Rock Currier.
Re: Pseudomorphs A to C
July 14, 2013 11:20PM
You're right, Keith, about how the copper found its way around the boulders in the Calumet conglomerate lode in the Copper Country of Michigan. The rounded casts, so to speak, are called "copper skulls" and are very difficult to find anywhere in the Copper Country both on the mine dumps or in rock shops.
Susan Robinso
(My husband George was curator at the A. E. Seaman Mineral Museum in Houghton, Michigan for 17 years and just retired).
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