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Identity HelpPyrolusite query.

2nd Nov 2015 15:43 UTCJay I. G. Roland

Hello all, apologies if this is in the wrong forum. My query is this, how come pyrolusite has such a disparity of hardness depending on if it's crystalline or massive? Mohs scale 2 - 61/2 is rather considerable so is there a simple explanation for this I wonder? I have never come across a mineral with so wide a range as this and only realised it as I am currently working with some lovely material (both massive & crystalline tabular/acicular) and was rather taken by how easily it cuts in the trimmer so looked it up on here.


Regards,


Jay.

2nd Nov 2015 16:45 UTCDoug Schonewald

Jay,


I was wondering the same thing. I recently collected some specimens that I was fairly certain were massive pyrolusite. Some are large pieces of almost entirely black mineral and others have smaller indistinct pieces throughout a quartz-type matrix. They are all exceedingly soft (around Mohs 3). When I looked it up on Mindat using physical properties it agrees that this is most likely pyrolusite based on hardness, color, streak, etc. etc. Then I went to the page and was surprised to see the hardness range. I am now rethinking whether this is pyrolusite or not.


Doug

2nd Nov 2015 18:57 UTCKnut Eldjarn 🌟 Manager

"Pyrolusite" has often been used as a name for massive or dendritic black Mn-oxides that on closer examination have turned out to be other minerals - i.e. Cryptomelane (H-51/2 - 6) or Todorokite (H-1,5). This could be the explanation if there is a wide variation in hardness for "Pyrolusite" in the literature.
 
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