Talk:Manganese dioxide

message: What does it smell like? --HomfrogTell me a story! 00:22, 20 October 2006 (UTC)
thread_title:  Smell 

message: Even diamond has a vapor pressure, steel too.
Anyway, the "other oxides" section is not relevant. If someone could put up some stuff on the synthesis of MnO2 it would be better than the stuff on KMnO4. It smells like damp chalk btw. And it stains you fingers brown! Spgoo1 03:18, 23 July 2007 (UTC)
replies: text: For as far as I can see, the formulas are balanced, I presume you are talking about the N2O4 reaction.  I count one Mn, 2 N, and 6 O on both sides.  Also, the age of a reference does not invalidate it (it might be follow up references that do, but which are missed here).  Could you please explain a bit further?  --Dirk Beetstra T C 08:39, 30 July 2010 (UTC)
thread_title:  Needs review 

message: This article is hard to read due to poor English usage. Quoting one particularly incomprehensible section: "Forms of MnO2 useful as an oxidizing reagent is not a straightforwardly stoichiometric reagent, far from it. The method of reagent preparation, sample history, and solvents are serious considerations."  I'd clean it up, but I have no idea what information those sentences are attempting to convey. 97.82.247.200 18:36, 10 September 2007 (UTC)
replies: text: Thanks for pointing out the strange English.  The section should be more comprehensible now.--Smokefoot 00:14, 11 September 2007 (UTC)
thread_title:  Unclear English 

message: Is metal oxides are electrical conductors rather than insulators?--Tohyf (talk) 04:08, 29 November 2007 (UTC)
thread_title:  Electrical Conductor or insulator?

message: The melting point of MnO2 is specified to be 535C which is significantly lower comparing with other metal oxides.
If possible, please provide references confirming this data.
If possible, please provide details on the decomposition process taking place at the melting point.
Especially the reaction products are of interest.
LSH0607 (talk) 12:59, 20 August 2009 (UTC)
replies: text: It's not really a "melting point" but a decomposition temperature. The figure of 535 ºC seems to come from WebElements, although  gives the same figure.  gives "about 530 ºC". The decomposition products are oxygen and manganese(III) oxide (Mn2O3). If you heat Mn2O3 even further (to about 1000 ºC), you will get Mn3O4. Physchim62 (talk) 13:46, 20 August 2009 (UTC)
thread_title:  Melting point 

message: Manganese dioxide also catalyses the decomposition of hydrogen peroxide to oxygen and water:
:2H2O2 → 2H2O + O2
:2H2O2 + MnO2  →  2H2O + MnO4
:MnO4  →  MnO2 + O2 (the catalyst is regenerated)
::The hereabove mentioned reaction was written without care and its electrical balance was incorrect. I have properly balanced the reaction, but I have no idea if the MnO4 substance [implying Mn(VIII)] really exists or is sufficiently stable to be handled in the lab. Not to be confused with the permanganate anion: MnO4–. In the doubt, I have not deleted this dubious equation, but it should be carefully checked. Thanks for your help. Shinkolobwe (talk) 16:55, 16 May 2010 (UTC)
thread_title:  Mechanism of the decomposition of hydrogen peroxide catalysed by manganese dioxide 

message: This section was deleted; I think it has value, but I didn't want to just re-add it. I'm not sure how these things are done. This was the deleted section (of course it's in the changelog too).
Manganese dioxide is believed to have been used in prehistoric times to start a wood fire. MnO2 lowers the combustion temperature of wood from 350 degrees Celsius to 250 degrees Celsius. Manganese dioxide powder has been a common find in Neanderthal archaeological sites.  http://www.nature.com/articles/srep22159  Heyes, P. et al., Selection and Use of Manganese Dioxide by Neanderthals. Scientific Reports 6 (22159 ), doi:10.1038/srep22159 (2016) 
Intrepidus (talk) 15:28, 3 March 2016 (UTC)
replies: text: Thank you for raising this issue, the section appears to have migrated to the article manganite, which is about the mineral form of MnO2. --Smokefoot (talk) 16:43, 3 March 2016 (UTC)

text: Second the idea that this information should be in the manganese dioxide article.  I added it myself, then after seeing in the history that it had already been added and deleted I deleted my edit, which pointed to the same article.  If there is a section on its use as a pigment by early humans--and there should be, then use as a fire starting aid should definitely be included, as well.  As the paper reports, the use of manganese dioxide to lower combustion is cognitively much higher on the scale than is its use as a pigment even if those using it were not specifically aware that the combustion point was being lowered. grifterlake (talk) 06:37, 4 March 2016 (UTC)
thread_title: Use of managanese dioxide by early humans

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thread_title:  External links modified 

message: We might move that material to pyrolucite, since the cave people used the mineral not refined form of MnO2 for their artwork.--Smokefoot (talk) 13:53, 26 July 2018 (UTC)
replies: text: I just moved the history and neanderthal content to pyrolucite.--Smokefoot (talk) 14:46, 29 July 2018 (UTC)
thread_title: Cave painting and Neanderthal stuff

message: Natural manganese(IV) oxide occurs as three polymorphs: pyrolusite, RAMSDELLITE and AKHTENSKITE. Hollandite not only bears BARIUM in addition to manganese, but its structure is actually a separate case. References: (1) https://www.mindat.org/min-3359.html; (2)https://www.mindat.org/min-71.html; (3) http://cnmnc.main.jp/; (4) https://www.ima-mineralogy.org/Minlist.htm Eudialytos (talk) 19:36, 29 September 2021 (UTC)
thread_title:  Strange mineralogy