[MSA-talk] wire iron

JOHN PAINE jbp3 at comcast.net
Tue Dec 5 11:45:50 EST 2017


I suspect that that iron is too electropositive to crystallize from aqueous solution under geological conditions. Alfredo Petrov rightly pointed out that most native iron forms from basaltic melts that encounter strong reducing agents (such as carbon). Wire formation among the coinage metals may be assisted by their electrical conductivity, allowing them to perform as electrodes. John B. Paine III


> On December 5, 2017 at 8:59 AM "Silverstein, Joshua" <silverj at miamioh.edu> wrote:
> 
>     Hi Jerry, 
> 
>     When gold precipitates from solution its crystal habit is dependent on the concentration of the gold. At low concentrations gold growth occurs as 2D growths where the growth is seen to preferentially deposit at steps, terraces and vacancies. With increasing concentration you move from 2D to dendritic (wire) growth. With higher concentrations gold hopper crystals are the dominate crystal form. 
> 
>     Why we do not see this in native iron I am not sure. Possible because golds outer electron shell is weaker and is more likely to exhibit dissolution/reprecipitation behaviors. 
> 
>     I recommend you contact my graduate adviser. Dr. John Rakovan (rakovajf at miamioh.edu mailto:rakovajf at miamioh.edu ) is a professor at Miami University (http://www.cas.miamioh.edu/~rakovajf/). He is very knowledgeable about native metals and has done extensive work with Gold and Silver. He is currently looking at dendritic silver wires (synthetic and natural) to understand the crystal growth habits of silver. 
> 
>     Cheers, 
> 
>     Josh 
> 
>     On Mon, Dec 4, 2017 at 5:52 PM, Magloughlin,Jerry <Jerry.Magloughlin at colostate.edu mailto:Jerry.Magloughlin at colostate.edu > wrote:
> 
>         > >         Two related questions: Is anyone aware of papers describing native iron in a wire habit, akin to
> >         what is sometimes present in native silver and native gold? I have a lot of papers on native iron
> >         and nearly all seem to illustrate or describe a generally granular or blocky or irregular habit.
> >          
> >         Second, why does a ‘wire’ habit develop in these isometric minerals? Any papers describing this
> >         would be much appreciated.
> >         Jerry
> >          
> >         Jerry F. Magloughlin
> >         Colorado State University
> >          
> >          
> >          
> >          
> > 
> >         _______________________________________________
> >         MSA-talk mailing list
> >         MSA-talk at minlists.org mailto:MSA-talk at minlists.org
> >         http://lists.minlists.org/mailman/listinfo/msa-talk http://lists.minlists.org/mailman/listinfo/msa-talk
> > 
> > 
> >     > 
> 
> 
>     --
>     Joshua Silverstein
>     Student Council Past-President, Microscopy Society of America
>     Editor, Micrograph of the Week, Microscopy Society of America
>     silverj at miamioh.edu mailto:silverj at miamioh.edu
> 
>     _______________________________________________
>     MSA-talk mailing list
>     MSA-talk at minlists.org
>     http://lists.minlists.org/mailman/listinfo/msa-talk
> 
 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.minlists.org/pipermail/msa-talk/attachments/20171205/d5f4ec4b/attachment.htm>


More information about the MSA-talk mailing list