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Improving Mindat.orgPseudomorph terminology

16th Feb 2017 13:21 UTCReiner Mielke Expert

It is my understanding that a specimen should be labelled as to what it now is, not what it was. In that case should this not be called pyrolusite? https://www.mindat.org/photo-148567.html

16th Feb 2017 14:20 UTCUwe Kolitsch Manager

Correct - message sent.

16th Feb 2017 18:56 UTCPavel Kartashov Manager

Dear Uwe,

if you remember the photo was initially uploaded as pyrolusite, but you insisted to change the label. ;-)

16th Feb 2017 21:49 UTCRalph S Bottrill 🌟 Manager

Pavel, Uwe asked you to change the name to Manganese oxides unless we have an analysis, and you haven't provide this yet. If its proven, it may be the first recorded pyrolusite dendrite? And how do you know it was vernadite if its a pseudo? Also neither pyrolusite or vernadite are listed for this locality so information is very welcome. Nice specimen!

17th Feb 2017 01:58 UTCPavel Kartashov Manager

For the moment this is mineral of Mn⁴⁺ - it produce pink coloration of strong H₂SO₄. apparently it was initially vernadite, but now it is dehydrated, I am think. I don't know exactly is it pyrolusite, nsutite or ramsdellite. But I feel that this is usual pyrolusite now.

I uploaded it, because in 2008 it was the best manganese dendrite photo in the database. Improve its description how you like or delete it at all. Frankly speaking, I'm tired of the discussions around this sample and already begin to hate it.

17th Feb 2017 02:29 UTCPavel Kartashov Manager

I am think, that in Gobi thousands of square km are covered by gravels with black desert suntan. This is mostly pyrolusite. Probably the same situation is in australian deserts. Yes, these stones covered not by obvious dendrites but films. But growth of these films beguns from dendrite formation stage, traces of which is still well visible on these desert stones - dense compact films has dendritic fringes.

These fine-disperse Mn-oxides heated by sun up to 80^o C and more during centuries. all this occurs under low humidity of air and low atmosphere pressure (altitudes over 1000 m and more). I don't think that hydroxydes of Mn will be stable in such conditions, because samples of manganite and vernadite dehydrating with formation of pyrolusite (var. polianite) even in more soft, hydrous environments (for example in Bakal and Kurganovskoe mines at Middle Ural).

> If its proven, it may be the first recorded pyrolusite dendrite?

This is pure casuistry. Yes, pyrolusite don't forms dendrites directly. But this don't means, that dendrites and dendritic films unable to consists of pyrolusite.

Limonite able to be composed by maghemite and hematite, while dendrites unable to contain pyrolusite... There is a typical system of double standards.:-( Or narrowness of mind.

17th Feb 2017 06:10 UTCDoug Daniels

Or, who is going to do a detailed analysis of each and every one of these, whether Mn oxides or Fe oxides (among other iffies)? Should we delete all such specimens/identities?

17th Feb 2017 07:10 UTCAlfredo Petrov Manager

We do have the option on Mindat of using the names "Manganese Oxides" - https://www.mindat.org/min-26664.html

- or "Manganese Dendrites" - https://www.mindat.org/min-26645.html - on species lists and photo headings.

17th Feb 2017 08:52 UTCUwe Kolitsch Manager

"Dear Uwe,

if you remember the photo was initially uploaded as pyrolusite, but you insisted to change the label."

The log file says I wrote:

"Is this analysed? If not, please change mineral name from "Pyrolusite" to "Manganese Oxides" and also change photo description accordingly."

You didn't change the label, but you added an explanation.

Later, Van King wrote:

"Hi Pavel,

I was looking through pyrolusite to see if there were any dendrites posted. As you may have seen, pyrolusite is not known in any dendrite in the world (Black "manganese dendrites" have never been identified as "pyrolusite". See Potter, R. and Rossman, G, 1979, Mineralogy of Manganese Dendrites and Coatings, American Mineralogist, v. 64, p. 1219-1226). I have spoken with Rossman recently and he says that no dendrite in the world has yet proven to contain pyrolusite."

Although I agree that pyrolusite is probable/possible, it would be better to keep pyrolusite only in the photo caption and use "manganese oxides" for the photo. This would be scientifically correct since there is no analytical evidence for the pyrolusite.

17th Feb 2017 21:18 UTCRalph S Bottrill 🌟 Manager

Pavel, don't hate it, it's a lovely specimen and generating important scientific discussion!

18th Feb 2017 03:36 UTCPavel Kartashov Manager

In situ, within initial "basalt" cliff (matrix of the sample is greenstone altered metasedimentary rock interlayered with basalt flows and diabase dykes) these dendrites were more brownish, dull and soft - they readily eliminated with toothbrush during washing (with formation of brown foam with soap). I specially spent some time for looking of the most black, lustrous, dehydrated dendrite specimen where them looks like as being painted by black ink. They not only dehydrated but and recrystalyzed also, compactified, lost fine-aggregate structure. You may to wash the sample by brush without any damage.

I am absolutely persuaded that initial vernadite (probably also not primary, but formed as oxidation product of manganite for example) was transformed (at least partially) into MnO₂. And pyrolusite is absolutely predominate polymorph of MnO₂ in the earth crust. How much localities of nsutite or ramsdellite do you able to remember!? While pyrolusite localities are countless and high-tonnaged. Pyrolusite usually predominates even within ramsdellite and nsutite localities. On any kg of nsutite or ramsdellite in earth crust we have some thousands tons of pyrolusite. So I think on 99.9%, that here pyrolusite is presented. I shouldn't to prove that this is pyrolusite at all - you should to prove that it isn't. Pyrolusite is the most stable at room condition modification of MnO₂ and all other manganese oxides/hydrohides tends to transform into it with time being extracted from their host environment. fine disperse manganite was quite able to transform into pyrolusite even only for 28 years of storage of the sample in my cabinet as it occurs with iron in amorphous hydro-silicate transformed into caryochroite in the same conditions. Take "manganese dendrites" from old museum collections and you will find a lot of pyrolusite in them as product of dehydratation of initial hydrous Mn species.. I am present to you idea of such research project.:-D

18th Feb 2017 04:01 UTCPavel Kartashov Manager

The reciprocal question - please look at head photos of pyrolusite mineral page. I have great impression, that all these "crystals" in reality are pyrolusite pseudomorphoses after manganite crystals.;-):-D:-D:-D

18th Feb 2017 12:40 UTCRalph S Bottrill 🌟 Manager

"I shouldn't to prove that this is pyrolusite at all - you should to prove that it isn't. "

If we made that rule for all photos we would have chaos here!

Pavel, I think the middle photo may be "primary" pyrolusite, but the other two probably are pseudomorphs - I have tested some similar ones by XRD and optical petrology so thats OK. But dendrites are harder to analyse: very thin films and very poorly crystalline, though may some spectral methods may work. Plus SEM/EDAX of course. But most people say "manganese oxides, boring, who cares?" But they are usually more complex that they look. It would still be great to prove that pyrolusite can form dendrites as other workers were adamant it does not, though I would be surprised if some was not.

19th Feb 2017 01:48 UTCPavel Kartashov Manager

Ralph, if you really wants to identify Mn phases in dendrites, you'll be able to do nothing without TEM electronography. PXRD and SEM will not help you great.

I spake about something another. I know that this dendrite consists of dehydrated vernadite at least partially transformed into pyrolusite. I know about presence of both these two phases in this sample. Why I should to use impersonal term "Manganese oxides" in this exactly case? Why not Vernadite or Pyrolusite, if I unable to write Vernadite/Pyrolusite?

This isn't some unidentified manganese dendrite - some experimental data were obtained from this material. I have genetical scheme of formation and transformation of this mineral assemblage. I am able to ask to check this sample on TEM, but and without these laborious and time-consuming researches I am know, what will be found here.

In yours suspecions, you putting me on the same bench as beginner collector, who dragged his tenth (hundredth - doesn't matter) stone from field trip. Don't you think, that my identifications (or may be foreknowledge) has some scientific background/basement? Why you apriori suppose, that they costs nothing? All the same, I'm not some sort of Raul Jorge Tauber Larry of Argentina with his foolish hopes, that this https://www.mindat.org/photo-601893.html allanite is Janhsite-(CaMnMg), but graduated geologist-geochemist with thirty-two years experience of mineralogical studies and systematic collector with forty years experience. My conclusions are not based on information gleaned from conversations at a local collectors club, but on deep understanding of laws of geochemistry, crystalochemistry and genetic mineralogy.

With such your approach, we haven't here no one photo of grossular or andradite, but only 'Andradite-Grossular series'. We have here 4 photos of "trevorite" from Bon Accord - noone of them are real trevorite but all are Ni-bearing magnetites. And what? It is very simple to confirm this with usual SEM EDX checking. Why don't you asking their uploaders to do this, but persistently requiring from me severe instrumental confirmation of identification of my sample, a photo of which I anyway already deleted?:-X

Enjoy now by pointless Raul Jorge Tauber Larry's picture https://www.mindat.org/photo-601932.html.:-D

24th Feb 2017 18:56 UTCRalph S Bottrill 🌟 Manager

Pavel,

this is not personal at all, I have great respect for your knowledge and opinions, but I just think it is good to question everyone and everything, this is how we learn. When I went to University for the first couple years we had to believe everything we were told without question, then in our third year we had a tutor that questioned us on what we thought we knew and suggested alternatives, and made us use reason not just memorise teachings. We suddenly realized that our professors and text books were not always correct and we were often better off to question our teachers and suggest alternative answers using logic and basic tests. When we question authority we sometimes get great logic and sometimes just beliefs and if we are asked to justify our own reasons and beliefs we can learn a lot ourselves. I am frequently wrong and am happy to be politely corrected with factual information. So I don't believe anyone is beyond questioning, no matter how many degrees, years of experiences, boards they sit on etc, we need to all be able to justify our thinking and keep an open mind.

So in Mindat there may be lots of things wrong and I question what I can, mostly in Australia but sometimes other issues catch my attention. This one is an issue I found interesting in that previous researchers have asserted that pyrolusite has never been found in dendrites but you say it does, so it's an issue worth proving. As with limonite being a mixture of poorly crystalline iron oxides, we can use the terms manganese oxides, wad, psilomelane, etc for poorly crystalline manganese oxides, nothing wrong with either term, but not very specific either. I agree things like garnets, tourmalines, amphiboles etc are commonly misnamed as a species when we should just use group names, but many people are desperate to give a species name with insufficient justification. We should be more rigorous at questioning these I agree. Re the Jahnsite, I haven't seen any discussion, but he claims to have tested it by XRD and XDR-TB, whatever that is, so until proven otherwise that seems reasonable?And similarly, calling nickel-rich magnetite trevorite, may be wrong but I haven't seen the photos or data, so please add these questions to the forums with specifics and we will try to follow them up.

So back to the main point. You argue that as the dendrites formed in a hot dry desert they must have dehydrated and converted to pyrolusite. But you commonly get surficial gypsum and clays etc in deserts, so without knowing more about the thermodynamics of the minerals I'm not sure if it proves anything? And you did a chemical test for manganese but I'm unsure if that can differentiate pyrolusite from other Mn oxides, probably most of which contain some Mn4+? At present there seems insufficient evidence to put any precise species name on it. Irregardless, I would accept whatever you wish to label it as, as long as you add your reasoning to the description. But remember when you are trying to overturn prevailing scientific theories or beliefs you do need to supply some good evidence. Please don't delete the photo it's a lovely dendrite whatever it consists of!

24th Feb 2017 19:46 UTCGregg Little 🌟

Ralph and Pavel; Please don't let feelings get in the way of excellent scientific discourse. I thoroughly enjoy the exchange. It is obvious that certain areas of mineralogy are increasingly vague (until rigorous research is applied) as the Mindat community expands. The important issue to keep in mind is that this site seems to be evolving into the go to site for the new arrivals to professionals alike. To that end, accuracy is paramount even where we have to be generalizing in the case of pyrolusite, for example. I am sure that in time the photos with accompanying descriptions and analysis will improve.

I particularly enjoy adding to the discourse about geological processes and rocks. Occasionally I feel I can provide insight to specific minerals or localities with the sole intention of luring another person into the hobby/science. Keep on rocking.

There is science in beauty and in beauty, science.

24th Feb 2017 21:14 UTCPavel Kartashov Manager

Ralph,

there is one of two, or you don't understand what I write (what is possible due to my poor English), or you sneering me.

So I see no reasons to continue this discussion. In any case I told all what I was able. You had not convinced me, and I hadn't you.

I am agree, that manganese dendrites don't contains singenetic pyrolusite during their formation.

I am strongly disagree, that manganese dendrites principially unable to contain secondary pyrolusite as product of their postgenetic oxidation and dehydratation.

Probably rereading of my texts will helps you to understand my position. Still my English is not so despairingly bad.

What about gypsum, I saw a lot of it from deserts, dehydrated up to bassanite. What about clays - it is bad example.

Lets finish on this.

25th Feb 2017 19:03 UTCJolyon Ralph Founder

Pavel, you've raised an excellent point and I think we must come up with better rules and systems for dealing with this.

How many 'torbernite' specimens are really meta-torbernite? How many of our borate photos are actually now photos of pseduomorph replcements?

We need to relook at our rules for this and define how such cases shoudl be dealt with, and provide better tools within the system to link these to the mineral pages for the original mineral.

Right now, for example, if we wanted to find everything that is a pseudomorph of garnet (for example), that is very very hard.

Jolyon

26th Feb 2017 06:27 UTCRalph S Bottrill 🌟 Manager

Pavel, I am certainly not sneering at you, I really enjoy and respect your contributions to Mindat. Perhaps it's a language problem, your English is quite good but unfortunately my Russian vocabulary does not go much past da, nyet, perestroika, Kalashnikov and Na zdorovie, which is probably just enough to get myself into serious trouble if ever I visit Russia! :-) Or maybe Australian culture, where we no not take each other too seriously or respectfully? Really it was just me wanting to learn from you how to differentiate specific manganese oxides without sophisticated analyses but I shall let it go.

I agree with your points that we cannot trust a lot of identifications in Mindat but we need people like you to point out problems and if we have time we will ask for more information to fix these things. A lot of this is down to people wanting precision rather than accuracy, we would be better off calling some specimens tourmaline or amphibole rather than guessing a species but that annoys many people.

Good point Jolyon about searching for pseudomorphs, the pre-pseudomorph mineral may be something that could be added in a separate field, perhaps only displayed when filled?

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