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Techniques for Collectors"Pyrite Disease"
19th Aug 2009 15:54 UTCRobert Simonoff
A while ago I went collecting with a club and found some nodules of pyrite or marcasite. They are beginning to catch "pyrite disease," cracking and crumbling. Will putting them in a closed box so that they are exposed less to sunlight help prevent further cracking and crumbling? Is there anything else I can do to prevent cracking/crumbling?
19th Aug 2009 16:21 UTCAlfredo Petrov Manager
19th Aug 2009 17:13 UTCRobert Simonoff
Thank you Alfredo, that was a very quick response! :)
What is a dessicant, and how do you achieve extreme dryness?
19th Aug 2009 17:22 UTCChris Stefano Expert
19th Aug 2009 17:27 UTCRobert Simonoff
Jessica
19th Aug 2009 17:41 UTCBarry Flannery Expert
I think that you will find that you need more than just a single packet. Also remember that the piece will have to be kept in an airtight container to prevent constant refreshment of humid air. The silica gel can only absorb a certain amount of water before becoming useless. At this stage it is useless.
Barry
19th Aug 2009 17:48 UTCAlfredo Petrov Manager
19th Aug 2009 17:59 UTCBarry Flannery Expert
What do you think the effects of keeping a specimen under a nitrogen atmosphere or a noble gas would be? Of course keeping it dry at the same time. I was thinking that perhaps the nitrogen would inhibit the respiratory functions of the thiobacillus ferrooxidan bacterias?
Barry
19th Aug 2009 18:11 UTCRobert Simonoff
How often should I change the silica gel pouches? (I don't have calcium oxide like Alfredo gets)
19th Aug 2009 18:21 UTCIan Jones Expert
19th Aug 2009 18:30 UTCAlfredo Petrov Manager
Barry, you might be right; I haven't tried it.
Some museums use sophisticated vacuum techniques to suck out all moisture and then inject lacquer into deep cracks to prevent future decomposition. Seems like a lot of work for a mineral as common as pyrite. I'd rather just throw out the unstable ones and concentrate on finding relatively stable ones. Unfortunately, most lesser preservation efforts seem to only slow the process down but not stop it completely.
19th Aug 2009 18:30 UTCDavid Von Bargen Manager
There are some chemical treatments that tend to inhibit pyrite disease, but they use some nasty chemicals and are often much more costly than the specimen is worth (mainly used on fossils). You should isolate these specimens from the rest of your collection.
19th Aug 2009 19:02 UTCStephen Moreton Expert
As a research chemist for what used to be Europe's biggest desiccant gel manufacturer I am, perhaps, in a good position to figure out how best to keep my pyrites dry. Storing in a desiccator with a suitable desiccant, is my preferred method, but laboratory desiccators are big and expensive. Recently I have begun experimenting with cheap, plastic, air-tight food containers, which seem to be just as good. Fill them to about a fifth or a quarter of their volume (the more the better) with dry silica gel (can be in a sachet for convenience) and place the specimen next to it. There are many other desiccants available too. For very low humidities molecular sieves (zeolites) available as little grey pellets, are particularly effective, although I've found silica gel to suffice (at least my pyrites stopped falling apart once I began using it). Clay based ones are cheap, but generally not as good as silica gel. These can all be regenerated by heating, although zeolites need a good cooking at about 400 degrees C to get them really dry. Silica gel can be freshened in the kitchen oven at about 110 - 150 degrees C for an hour. Indicating varieties are available that change colour when used up. The traditional one uses cobalt chloride and turns from blue to pink. Turns blue again when baked in an oven to refresh it and can be used many times over. As cobalt salts are slightly carcinogenic I invented one based on iron which goes from amber to near colourless (United States Patent Application 20040209372). A variant I came up with later uses a Fe-bromo complex and gives a better colour change at even lower humidity and is manufactured under licence by Engelhard (as "Sorbead Orange Chameleon" ), although I am not sure if it is available to non-industrial consumers, but would be the best one for the job. Both can be refreshed in the oven many times over. Some people use a microwave oven, although temperature control is harder. There are other indicating silica gels, but those based on organic indicators (commonly blue/yellow colour change, although there are others) tend not to withstand many drying/redrying cycles. I have no qualms about using the traditional blue/pink cobalt-based one for my samples however, and it is probably still the most readily available. Just don't eat it!
As Alfredo says calcium oxide is an even more powerful desiccant (drying agent), however, unlike silica gel, it cannot be regenerated (except in a furnace). It is also very alkaline. Where I have found it useful, however, is in treating specimens in the early stages of pyrite rot. For this one needs a large air-tight container (a desiccator is ideal, although I guess a particularly large food box will do as long as it is air-tight). Fill a small beaker or pot (100 ml) with calcium oxide ("quicklime", best as lumps) and place it in the container. Place the specimens nearby in the container. Add a few ml of strong ammonia solution to the calcium oxide and put the container lid on fast. The calcium oxide reacts with the water in the ammonia solution, setting the ammonia free as gas. Leave for several days. Being a small molecule ammonia can penetrate into the tiniest spaces in the specimens, neutralising any sulphuric acid within them. It will thereby bring to a halt any pyrite rot, but will not repair the damage already done. Do this treatment in a well ventilated space (NOT in the house) as ammonia stinks. I use my garden shed. When done take the lid off (outside) and leave for 20 minutes for the smell to go then get the specimens into an air-tight container with desiccant as discussed above. If the specimen is already badly affected you may see some brownish colouration (hydrated iron oxides) where the products of the pyrite rot have reacted with the ammonia. In that form they will do no more harm, but rot will resume if the specimen is ever exposed to atmospheric moisture again, so keep it in its container and only bring it out briefly for ceremonial occasions.
19th Aug 2009 19:09 UTCRobert Simonoff
19th Aug 2009 20:35 UTCBen Kirchner
Thanks that is a pretty interesting comment! I love hearing stories about mine fires. Do you know about the fire in Jerome, AZ? The sulphide body caught on fire, burned for about 30 years, and created a whole suite of interesting new minerals.. Pretty cool history! Thanks for sharing that all that information!
Ben Kirchner
20th Aug 2009 08:37 UTCRay Hill Expert
Thanks Stepen!
You and Alfredo always seem to come up with
interesting and thorough answers.
20th Aug 2009 14:38 UTCRobert Simonoff
21st Aug 2009 05:42 UTCRock Currier Expert
I think that is the best thing written to date on treating degenerating pyrite and Marcasite. Would you consider writing it up in a somewhat more formal sense for an article here on mindat. I would like to post it up in the welcome section of this forum to refer people to when they ask about this problem. If enough people address the more common aspects of cleaning and preparing mineral specimen, we will eventually have a pretty good manual for cleaning and preparation.
21st Aug 2009 07:00 UTCRobert Simonoff
Thanks
Bob
21st Aug 2009 08:12 UTCRalph S Bottrill 🌟 Manager
21st Aug 2009 13:07 UTCAlfredo Petrov Manager
21st Aug 2009 14:12 UTCjacques jedwab
21st Aug 2009 15:51 UTCMark J. Sigouin
Just as an aside, this it the basic reaction that occurs in the formation of acid mine drainage.
21st Aug 2009 17:29 UTCDavid Von Bargen Manager
http://www.vertpaleo.org/education/documents/Shinya_and_Bergwall_2007.pdf
http://collections.paleo.amnh.org/6/storage-environments
Government recommendations:
http://www.nps.gov/history/museum/publications/MHI/AppendixU.pdf
Matrix can cause problems as source of water - re: halloysite
Under these conditions, relative humidity is unimportant: water for the reaction comes from a local source, and hydrous iron-aluminum sulfates act as “getters” for more water. Drying the materials worsens the problem by producing a dust that easily spreads to seed pyrite disease in other specimens. These seeds rapidly re-hydrate at higher humidity.
21st Aug 2009 18:00 UTCAlbert Mura
21st Aug 2009 20:23 UTCGord Howe
I worked at the Sullivan Mine in Kimberley BC in the 70s and early 80s and have seen sulphide oxidation first hand. The mining procedure at the time was pillar mining where they would drill and blast a large volume of rock called a pillar then muck it out. The process left tons of sulphide based ore open to air where it would start oxidizing to the point where the rock would actually melt!. You can imagine the logistical problems this would cause with equipment, manpower etc. The main minerals were galena, sphalerite, pyrrhotite, and many other minor sulphides. Locally this phenomena is well documented and I'm pretty sure one of those old miners would be happy to share a "hot muck" story.
Gord
11th Sep 2009 11:43 UTCAnonymous User
Please search for topic:
"Thiobacillus ferrooxidans" 2 years ago.There is an extended conversation about the same subject.Killing the bacteria and keeping dry won't help stopping the decomposition.
I'd like only to note here that the compounds required to stop the decomposition are very expensive!One should try only when talking about very important specimens.I have Pyrite from Madan only and I keep them in open air,I even clean the with acids and I wash them with water.They are so stable that even old pieces that had such treatment long before i handle them are still pristine and intact.It depends on many factors but the locality is very important!
All the best!
-Kostas.
24th Oct 2009 12:26 UTCJeroen Goedhart
There is a tiny chance that all instable ones were lost anyway and I painted only the stable ones, it's 20 years ago....
1st Mar 2011 20:19 UTCMary Jansson
I found a rock ~ The rock is heavy for it's size ~ weighing 11.5 ounce's.... It measure's three and three quater's inche's long and is Two inche's wide.... The rock appear's to have quartz also a redish brown coating in some area's.... I wanted to see what was inside, so I took a little saw and tried sawing into it.... On the inside it is just full of bright and shiny silvery color of what I suspect is Pyrite.... Also has numerous cubicle's of golden color.... I did a streak test on rough tile and the streak is black on most ~ also golden on other area's ~ what kind of rock do you think it is and should I do anything to protect the pyrite? Doe's the mineral gold ever mix in with pyrite in a rock? It is a very unusual looking rock and very heavy for it's size....
1st Mar 2011 21:31 UTCReiner Mielke Expert
1st Mar 2011 21:37 UTCJolyon Ralph Founder
1st Mar 2011 22:58 UTCBob Southern
2nd Mar 2011 01:01 UTCPaul Brandes 🌟 Manager
3rd Mar 2011 04:07 UTCJim Bean 🌟
3rd Mar 2011 10:53 UTCJolyon Ralph Founder
3rd Mar 2011 17:05 UTCDonald Vaughn
3rd Mar 2011 21:31 UTCReiner Mielke Expert
Or you can just scoff, not do the treatment and lose your specimen.
3rd Mar 2011 21:52 UTCJolyon Ralph Founder
But I have some samples that I fear for the future, so I'm going to test them with reiner's idea - I certainly can't see how it can do any harm, so I'm prepared to give it a try!
Jolyon
14th Mar 2011 21:27 UTCJohn Mason
Something to consider too.
About 12 years ago I collected some amazing micros of reticulated pyrite from a mine in the Dolgellau Gold Belt - some of you may have seen a UKJMM note on them.
Some I hung onto, others went to a museum.
Where I lived at the time, 300m ASL in Wales and with hopeless heating, temperatures rarely went above 10C except for occasional heatwaves in the summer months - and then not far above! Humidity was often high, as one would expect in Wales. That is quite normal.
The museum was air conditioned and warm throughout all year round. The specimens I retained lasted just fine - the ones at the museum were dust within a couple of years. I figured temperature to be a major factor based on these simple empirical observations.
I think some varieties of pyrite will inevitably disintegrate quicker than others, but heat pushes the reaction along, based on these observations. Some others will clearly last a long time - I have Spanish and Peruvian pyrites >20 years in my collection that are the same visually as when purchased. Central Wales - my patch - produces some nice marcasite crystals at some localities, but frankly they are hardly worth collecting, as they "go woolly" withion 12 months and that's the first step to a heap of sulphurous powder that can knacker up even stable choice sulphide pieces from elsewhere!
Cheers - John
23rd Mar 2011 06:33 UTCAnonymous User
Please search for :
Thiobacilus Ferroxidans
in this forum.
Success!
-Kostas.
27th Aug 2011 01:47 UTCDavid Zimmerman (2)
While that technique sounds extreme, it has worked flawlessly for over 15 years on that piece and I doubt many of you would question the procedure if I was to produce before and after pictures.
Expanding off from that technique, and working with its success, I've since stabilized dozens of pieces of both pyrite and marcasite by first cleaning off any sulfur using abrasive measures. Then I put a thin coating of some light oil (WD40, mineral oil, or similar) on and bake it in the oven for at a low setting for 2 hours. Remove from oven and serve (:P). Joking aside, as soon as it is able to be handled (couple of hours later), I then spray the piece with an acrylic finishing spray that I buy at a craft supply supply store. It is used as a top-coat spray over artwork such as chalk and pencil to keep from smudging. I use a mat finish and can not comment on the gloss finish. I wait until it is dry and put a second and third spray coating on, depending upon the porosity of the material. Some pieces I have done as many as 5 coatings on.
This revised technique has worked well for me over the last 3 years and I have not seen any degradation of the pieces nor have I smelled any sulfur odors from them either. They are stored in a high-humidity area right inside my glass showcases for the world to see...not in some special containment area.
This is very similar to the other success story written above where the man used fingernail polish to seal it off. I find that the acrylic finishing spray is undetectable to my eye, and I'm sure it would pass the muster for 99% of the people reading this.
For Albert Mura above: Please PM me and I will be happy to pay for the shipping on all the pyrite that you are throwing away!! :D
27th Aug 2011 14:45 UTCPeter Haas
I assume it is relative humidity you refer to. Now, if you had 75% relative humidity at -5 °C and 5% relative humdity at 45°C, this really wasn't much ...
27th Aug 2011 19:39 UTCDavid Zimmerman (2)
Some pyrite and marcasite pieces are from old locations and can not be replaced at any cost. I would value the price of the piece that I previously mentioned (the one I used Rustoleum on) well north of $1,000 and like I said, it just can not feasibly be replaced, unless someone wants to pump out 1,000 feet of mine water.
I have a hard time tossing or destroying material that took millions of years for nature to produce. I often consider myself the temporary caretaker for all of my minerals and try to preserve or clean them to the best of my abilities.
28th Aug 2011 01:12 UTCAnonymous User
Yes Peter I was talking about relative humidity and the maximum and minimum ranges my rocks have experienced during their travels across the Australian continent, and no not 75% at -5C, the values given were to show the wide ranges in both humidity and temperature my rocks have been exposed to and survived - including two cyclones. The causes of pyrite rot are complex for which there is no easy solution or answer. When I lived in Western Australia near the shores of the Indian Ocean, in fact just about 100m away from the shores I did a little test on a piece of fine grained pyrite I got from the Mt Isa Mines. I left it in the garden, in damp soil for over a year and it survived the test. I had a specimen of coarse grained galena which I collected during an underground trip to the Broken Hill Mines in 1997. It had a small quantity of associated pyrite and in less than a year the pyrite had completely decomposed to a white powder. Luckily the galena survived. Later I will be posting some photos of my pyrite disco balls from China. These balls had been kept in very damp conditions in a shed in China for well over a year, yet they show no signs of decomposition.
There was an article I read sometime ago about work done in a museum, the British Museum I think and the techniques and chemicals they used on decomposing "pyrite" fossils. They solved the problem I think but the procedure is not one you could easily do at home nor could you purchase the chemicals without some difficulty or expense.
And David I wish you all the best with your $1000 Pyrite specimen. Please post some pictures I would love to see it.
28th Aug 2011 02:17 UTCRalph S Bottrill 🌟 Manager
Pyrite disease is often related to inclusions and substrates of other minerals, especially marcasite, but possibly other metastable Fe-S-O minerals. These often form from the breakdown of pyrrhotite, which usually forms a lot of marcasite as well as pyrite and other minerals. I imagine that galena from Broken Hill would have been on pyrrhotite originally, but this mineral can be a lot more altered than it looks.
28th Aug 2011 21:06 UTCDavid Zimmerman (2)
Here is a picture of the piece that I used black Rustoleum on to seal.
This again, was my first attempt 15 years ago when I was 18 at the time. I'm still very happy with the results, but maybe someday I will abrade the surface a bit to take the gloss off. You will notice a pile of sulfur in the showcase where a second piece of marcasite has left its tell-tail sign....someday maybe I'll get around to sealing that one as well, but the matrix on the piece is substantial enough for me not to worry about. The pen is for scale as well as pointing to the repaired area. What is strange about decomposing marcasites and pyrites are that the little marcasite flowers on the piece have not been sealed and appear to be stable. The only unstable crystals were attached to the matrix and not perched on the sphalerite xls. Largest dimension on the piece is 14.5" with a 3.25" galena perched next to the pen.
Here's a picture of pyrite balls perched on lepidodendron root that I found a few years ago.
I think the pyrite is not quite as shiny as I remember, but I could also be remembering the gloss on the other 100 I picked up and possibly this one never had it....it was just too long ago. Either way, the pieces that I chose not to seal are just piles of dust right now and this one still sits in my showcase. Largest dimension is 7 inches.
1st Sep 2011 08:11 UTCAnonymous User
Fixative spray and other coating will work on a specimen where decomposition hasn't started yet.
However,this hides the luster.
Also,temperature of the oven and oils can damage some Pyrite.
But,the most important note here is the interaction of the conservative methods with other specimens!Many recommended desiccants and this is correct-please read the post I recommended.
However,keep the desiccants away from hydrated species-I imagine there will be a problem.
I'd like to express my happiness when I realize how many people like Pyrite! I believe that it's the wide use of metals in our lives that makes many collectors call all metallic lustrous species "ugly black". First, someone who's seen a lot realizes that they do have color-there is obvious different between Galena and Tetrahedrite-and second I don't think they are ugly at all!I stop that here,but I couldn't resist expressing myslef!
12th Oct 2011 22:48 UTCReiner Mielke Expert
13th Oct 2011 00:25 UTCMichael J. Bainbridge Expert
13th Oct 2011 00:57 UTCReiner Mielke Expert
13th Oct 2011 01:17 UTCAnonymous User
13th Oct 2011 01:24 UTCMichael J. Bainbridge Expert
As for iron-out on pyrite and marcasite, I've not tried it yet either, but I'm told that it does a good job taking the dull tarnish off Nanisivik pieces. When I get up the guts to try it on mine I'll let you know.
Cheers,
Michael
13th Oct 2011 12:31 UTCReiner Mielke Expert
For the same reason people buy an antique car, because they don't make them anymore. Also this is not just about preserving old pyrites but preventing new ones from deteriorating. Think of it as rust proofing a new car.
13th Oct 2011 14:56 UTCBart Cannon
"Pyrite Disease" is caused by thiobacillus bacteria. They need some moisture to survive, as do all bacteria..
Apparently only an old timer such as myself knows that soaking an iron sulfide in a bacteriacide is the cure.
The product known as "Janitor in a Drum" worked well, but I don't know if it is still available.
There are surely other bacteriacides in the modern marketplace.
Nothing sadder to a mineral person than to see a beautiful pyrrhotite crystal cluster become 500 crumbs.
In the technical ore mineralogy literature there is a texture known as "chalcopyrite disease".
Not related to "pyrite disease". It is the un-mixing of copper in sphalerite and produces small blebs of chalcopyrite in sphalerite.
13th Oct 2011 15:19 UTCMichael J. Bainbridge Expert
13th Oct 2011 15:56 UTCJolyon Ralph Founder
If it were, it would be as easy as Bart suggests to cure. While, in some cases, bacteria may increase the speed of reaction, exposure to moist air can kill pyrite regardless of how it has been treated.
If you want to know the latest research about pyrite disease, ask a palentologist - they are much more concerned about pyrite decay than mineralogists are. Loss of a pyrite crystal is no big deal, but when your type specimen of an important fossil is pyritized, you really want to make sure it stays intact.
Jolyon
13th Oct 2011 16:04 UTCBart Cannon
Alcohol contains water and adsorbs additional moisture from the air. It then evaporates leaving the specimen moist and host to occupation by residual bacteria.
Bacteriacides linger and can function even if moisture is present.
I've never seen a true study on this, and only speak from notions of what I've heard elsewhere. I've never actually tried Janitor in a Drum.
I also have many ruined marcasites and pyrrhotites. Painful. I may seek out a modern bacteriacide and run a crude experiment.
The idea began with the problem of Tri-State marcasites disintegrating on their museum shelves and in the collection drawers.
Tri-State being the celebrated lead - zinc mines near Joplin, MO, Picher OK, and Kansas. I think there's a little bit or Arkansas in the district as well.
Bart
16th Oct 2011 09:09 UTCPeter Haas
I do not wish to offend anyone so I am going to play the devil’s advocate here. You would not buy a car with significant structural rust nor a house overrun with termites so why invest in a “rotting” pyrite specimen.
There may be other minerals associated with the pyrite which are much more interesting. The classic galena after pyromorphite specimens from Wheal Hope, Cornwall, are often associated with pyrite that is particularly susceptible to decomposition. The same holds for many classic Wheal Jane ludlamites: they sit on pyrite.
16th Oct 2011 09:48 UTCBart Cannon
When it comes to bacteria and minerals, never say NOT. The bacteria don't cause the minerals to crumble, It is the byproducts of their metabolization that expand and disintegrate a specimen. They get their water for free from the air they drink and breath.
Every day we learn more about how pervasive bacteria are. 20 years ago we learned that stomach ulcers were not caused from stomach acid but rather the bacteria Heliobacter pylori.
Though I was challenged on this, I say automobile rust bubbles are caused by bacteria. Perhaps gray and brown rust primer paint doesn't seal against corrosion as much as its composition kills bacteria. Primer doesn't work unless the rust bubble is popped and scraped to eliminate the lovely, moist bacterial playground inside a rust bubble.
Bart
16th Oct 2011 11:56 UTCAnonymous User
I think I said that too! Did you read my comment in full? We are not talking about that here, are we? Rather we are talking about someone’s rotting specimen. It is only my opinion but I would not risk “cross-contamination” or damage to my other beautiful pieces just to save some average looking rock that is falling apart. Sorry, but it is very easy and relatively inexpensive to get some real killer Peruvian or Spanish pieces I would not waste my time. I would leave the restoration work to the experts who are trained to do this type of restoration on samples of real scientific importance – archeologists/paleontologists/surgeons.
17th Oct 2011 05:59 UTCDavid Garske
Dave
17th Oct 2011 06:24 UTCAlfredo Petrov Manager
17th Oct 2011 10:48 UTCJolyon Ralph Founder
17th Oct 2011 15:15 UTCAnonymous User
I have to agree with Bart.To my knowledge,it's Thiobacilus ferroxidans that "eats" Sulfur and katabolizes Sulfuric acid.I'm not sure about the exact biochemical reaction,I couldn't find information on the bacteria,since it's not pathogenic,but without the bacteria there is no acid,so there is no decomposition.
17th Oct 2011 15:40 UTCDon Saathoff Expert
Don
17th Oct 2011 16:43 UTCJolyon Ralph Founder
"Some bacteria does eat (and can decompose) pyrite
therefore all pyrite decomposition is caused by bacteria, and treating your pyrite with a bacteriacide will protect it."
Unfortunately it's just wrong. Pyrite can decay with or without the presence of bacteria. While it's possible bacteria will accelerate the process, the real killer is relative humidity.
Keeping your pyrite dry is the only genuine way to protect it.
18th Oct 2011 06:21 UTCPeter Haas
Oxidation: S2- + 4 H2O -> SO42- + 8H+ + 8 e-
Reduction: O2 + 4 H+ + 4 e- -> 2 H2O
Thus, the oxidation of sulfide to sulfate produces as many protons as the reduction of oxygen consumes (sulfide -> sulfate requires two mols of oxygen). However, when oxidation starts from sulfur in a higher (more positive) oxidation state than sulfide (which is the case for pyrite and very few others that are composed of polysulfide anions), the reaction produces more protons than electrons and the solution turns acidic.
For all other sulfides, acid is only produced when metal ions (predominantly iron and manganese) precipitate as hydroxides, leaving protons behind, e.g. Fe3+ + 3 H2O -> Fe(OH)3 + 3 H+
18th Oct 2011 08:57 UTCBart Cannon
If one could truly keep their iron sulfides ABSOLUTELY dry, then your opinion is correct.
But, of course, that is not possible, even in a partial vacuum.
There are splitters and clumpers in mineral classification, and a new dichotomy exists.
Bacteria believers and Bacteria deniers.
Some micro-biologist / mineralogist out there should do some cultures.
I have purchased some books on bacteria taxonomy, but there would be no reason for anyone to believe my findinds.
I have some pyrite liquors brewing, but the contamination factors will prevent any definitiave conclusions.
Bart
18th Oct 2011 09:54 UTCJolyon Ralph Founder
So, perhaps all pyrite specimens are mortal and will eventually decay. But the dryer you keep them, the less chance they will turn to a powdery mess in your lifetime.
Of course, treat them with a bacteriacide, it will do no harm, but it is terribly harmful advice to tell people that this alone is enough to keep specimens safe.
18th Oct 2011 11:40 UTCAmir C. Akhavan Expert
In the case of pyrite and marcasite, isn't that
2S22- + 2 H2O + 7 O2 -> 4 SO42- + 4 H+
?
I might have missed something here...
Note S2- vs S22-
18th Oct 2011 12:19 UTCPeter Haas
EDIT: I have added a note to my previous post to make this a bit clearer (hopefully).
18th Oct 2011 17:29 UTCD Mike Reinke
This has been a great thread, I appreciate all sides, (and it has stayed civil....., so far!!) When I first got into minerals, I noticed in some old rip rap near my place, that most pyrite was dull but a few specks or even larger bits were very shiny still, having sat exposed for at least 20 if not 40 years. Of course, being a newbie, and ever optimistic, I thought maybe it was the trace content of gold that was so non-corroding, cha-ching! Later I read more on the subject, but this thread is even better. Thanks.
Mike
23rd Oct 2011 05:24 UTCDavid Zimmerman (2)
Bart, I've got a lot of love for you but I agree with Jolyon that Bacteria can not be the sole cause for every case. This is evident in the picture I posted where the primary deposit is decomposing, yet the secondary flowers are stable. In the sealed area the two types of marcasite are touching each other.
On a related note: I was digging in an old WI tailings pile a few years ago and was seeing typical iron rusty blebs (completely decomposed marcasite xls) on the pile material but was shocked to find material that looked fresh-as-the-day-it-was-mined only 3 feet under the surface of the pile. I was shocked! ::o
I'd love an explanation from the pyrite gods on that one. Over 100 years of rain, moisture, and plenty of opportunity for the bacterial culture to create it's pile of paradise, and yet perfect crystals only 6 inches away from decomposing ones.
23rd Oct 2011 11:25 UTCNicu Pascanu Expert
I wouldn't want to be misunderstood here, this is just a test that could have only positive response in some specific conditions.
Cheers, :)
9th Sep 2012 03:34 UTCMatt Zukowski 🌟
It could be that the reason that the pyrites and other sulfides are fresh only three feet below the surface is that there is too little oxygen at that depth. Redox gradients can be quite steep with slow movement of water in a porous media. In this case, although the water falling on the site is oxygenated, as it infiltrates it quickly becomes oxygen depleted, so the oxidizing environment extends only a short distance into the subsurface.
9th Sep 2012 13:49 UTCBart Cannon
The age old bacteriacide for saving marcasite was Janitor in a Drum. It has long since lost its retail neighborhood oulets. It is still available from a single central supplier, but only in large volumes.
The reaction pathways in the weathering of sulfides is incredibly complex. An almost endless series of intermediate and transitional phases..
There is an excellent book on this subject.
"Oxide Zone Geochemistry" P.A. Williams, 1990. Ellis Horwood Publishers.
I'm still curious about the process which produces museum drawer acanthite fuzz.
Bart
23rd Apr 2013 19:45 UTCJohn Oostenryk
I figured I would chime in here- since this is where Reiner's methodology was first posted.
As many other posters reacted at that time, I also was amused/disgusted when I read Reinier's proposed method with oiling. I thought, "Good God- what a mess! The guy must be crazy!"
BUT- after realizing a local connection between oil/bitumin pockets associated with long exposed and completely intact marcasite crystals... and therefore, some later, related reflection...
I resolved to engage in an ongoing product test with various control groups to account for none/some state of decay prior and variety of inside/outside environment factors.
I couldn't bring myself to do the glooping oil factor, but did use full immersion in WD-40...
So, the reveal?
Earlyyyy results are- at an ~year and a half and continuing, nooothing is changing on my marcasite/pyrite pcs... So good news so far...
...I intend a report of my results with details and pics for Mindat- it is pending- no hurry...
But,
Thought it would be good to get that positive data out sooner for my fellow mineral collectors, who hate the sad scene of trashed minerals and despise the smell of decomposing Marcasite!
(There is some putting up with the WD-40 during processing, but that is what garages are for:)
Cheers,
~JO:)
ps: Jolyon- what do you see in your project version so far?
23rd Apr 2013 20:14 UTCTim Jokela Jr
Rest assured that Reiner is far, far from an idiot, and his method makes sense. Bacteria or chemical reaction, it deals with both.
He's a 4 decade fanatical field collector / prospector / geologist / miner, ingenious at mineral ID and prep, and is not short on brains.
NO gloop is involved in the Mielke Method! The oil I used on my old rotten pyrite drained off fully... it's not at all what you'd think. The piece looks perfectly clean and there's only an odor if you put your nose right up to it.
I'm kicking myself for not having the balls to similarly treat a 3" pyrite pseudo after pyrrhotite, which turned to $175 worth of dust.
To all in doubt, try it out!
It's cheap, and easy...
just like the girls I like.
23rd Apr 2013 22:28 UTCJohn Oostenryk
I changed my wording to better relay the minor content of my post, it seemed to impinge a bit, and I fully did NOT intend that interpretation...
BUT, oh yes- shocking? of course! Same as if someone said dip them in syrup! Gnarly-lol!
I actually do suspect the oil cuts the WD-40 vapors too?! So shoulda went all the way with some... I'll try that too yet, no doubt~
The major point was, as you know, to relate that THIS IS, very successful so far. Two positive reviews at one time are louder than single statements here and there!
I felt it best to get that news out to folks now, as I have been waiting quite a while. Some science is slowwww-LOL. Patience IS a virtue.
I thoroughly relish a 'successful pretreatment process' to avoid that stinking nasty odor of decomposition!!!
I have done some serious cleanup in other venues of old specimens which had formed huge piles of friable 'dust'. Gack- it was so horrible!
Anyhoo, gotta fly, but I had to rectify that misunderstanding for Maggie, she is always so pleasant, I was truly bummed to see her wroth:(
Best,
~JO:)
23rd Apr 2013 22:59 UTCMaggie Wilson Expert
I'm better now. Thanks, John, for your remarks.
Maggie
23rd Apr 2013 23:57 UTCJohn Oostenryk
I'm glad you brought it to my attention- I should have waited till I had more time to post a better rendition of what I was trying to convey...
...Figures- I spent 4 times as much time trying to sort it out~ack!
Thanks for the understanding:)
~JO:)
23rd Apr 2013 23:58 UTCMaggie Wilson Expert
Cheers!
Maggie
24th Apr 2013 07:58 UTCLuca Baralis Expert
Dessicant can help, but just before it starts. Afterwards you can try to remove internal humidity and acid with a bath in alcool, but in my experience I can't assure it works. Furthermore, If the specimen is internally damaged it can easily break up and disgregate.
Luca
8th Nov 2019 02:12 UTCDavid Zimmerman (2)
I'm not sure if it adds anything to the theories, but I remember one time prepping a bunch of pyratized lepidodendron roots and I think I put them in some HCL overnight and was horrified the next day to see that the rot was ACCELERATED and I was left with stinky mud in the bottom of the bucket with just a 24 hour soak. Whatever the culprit actually is, it THRIVES in that acidic condition.
Also after re-reading this topic, I would have a hard time believing that there wouldn't be any oxygen in a tailings pile just 3' under the surface when you have oxide zones in historic districts that go down hundreds of feet.
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Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: April 25, 2024 22:15:13