[Rockhounds] Cleaning Galena, Help?

[Lawrence Rush]

Well...maybe not dead, but moribund!

Some acids will help, if not restore to original luster. See....

http://www.connroxminerals.com/Galena.html

This was a quick soak in sulfamic acid, and a brush with an old toothbrush. 
The alteration was not gray, as in Kevin's case, but more black (lead 
sulphide?), but it does make the specimen more attractive.

Some Galenas are more amenable to cleaning than others. I don't know if this 
is due to the type of chemical weathering, or the crystallography (In some 
cases, one face will clean while an adjacent one will not).

Larry


----- Original Message ----- 
From: "R. Peter Richards" <rpr at heidelberg.edu>
To: "Rockhounds at drizzle.com: A mailing list for rock and gem collectors" 
<rockhounds at lists.drizzle.com>
Sent: Thursday, June 19, 2008 9:35 AM
Subject: Re: [Rockhounds] Cleaning Galena, Help?


> What has not been said so far in this thread is that the weathering  takes 
> place by chemical alteration of the surface of the crystal. 
> Consequently, the original luster of the crystal surfaces is gone,  not 
> just covered up.  Even if you can completely remove the altered  material, 
> you cannot restore the original luster.  Physical methods  such as use of 
> abrasives can create a new luster, but it's an  artificial one.  Chemical 
> methods that remove the altered material  will not bring back the luster. 
> Let's face it, them crystals is dead!
>
> Pete Richards
>
>
> On Jun 17, 2008, at 11:18 PM, Paintricks at aol.com wrote:
>
>> Hey everybody.  I have some nice Galena crystals that have an   oxidized
>> coating i need off.  It's a dull grey like your tire weights have   after 
>> a few
>> thousand miles.  This stuff is beautiful underneath.  Any   suggestions?
>>   Thanks in advance,
>>   Kevin
>>
>>
>>
>> **************Gas prices getting you down? Search AOL Autos for
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>>
>>
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> ___________________________________
> R. Peter Richards
> rpr at heidelberg.edu
> Morphological crystallographer
>
>
>
>
>
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