[Rockhounds] Pyrite disease

[Rik Dillen]

Some thoughts about "desinfecting" pyrite aggregates before decay :

1) A suitable product to kill any bacteria would be "Neo-Sabenyl" solution (active compound : chlorophene
(O-BENZYL-P-CHLOROPHENOL)), which is used to desinfect surgical tools (and parts of the body). This is a non-aggressive
product, that penetrates quite well in porosities.
2) I doubt seriously that any solution can reach internal inclusions of framboids in pyrite aggregates or other internal
features. I'm wondering if any (non permanent) solution treatment would help.
3) If the cause is bacterial, it should be possible to eliminate the threat by just heating up the sample for a short
period to 140°C.
4) I think that more than one mechanism could be responsible, with a possible role for bacteria, relicts (as micro-fluid
inclusions ?) of the original acid solution from which the aggregates was formed, traces of sulphates, free sulphur
etc.). That makes it so difficult to find one method to cure all cases.

My 2 eurocents...
Greetings, 

Rik DILLEN 
Doornstraat 15,  B-9170 Sint-Gillis-Waas 
Belgium 
E-mail rik.dillen at skynet.be 
Homepage : http://users.skynet.be/rik.dillen 
 
MINERANT 2008  -  26-27 April 2008
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Jan Van Rijswijcklaan 191 Antwerpen 
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Mineral collector's page http://www.minerant.org/ 

-----Original Message-----
From: rockhounds-bounces at lists.drizzle.com [mailto:rockhounds-bounces at lists.drizzle.com] On Behalf Of Juergen Wachsmuth
Sent: Friday, December 28, 2007 11:22 AM
To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors
Subject: Re: [Rockhounds] Pyrite disease

Hello,

tetracycline cannot harm all kinds of bacteria that may exist in / on rocks.
Its efficacy does not even cover all bacteria that may cause infections in
humans. Moreover, it does not kill bacteria, it prevents bacterial growth as
long as it is active. Surviving bacteria will be active afterwards.
Therefore I suggest you should choose a desinfecting substance for your
purpose. Alkohol 70-80 % could be efficient. Ready to use solutions for
desinfecting hands contain additives that make them more powerful, but may
leave a residue on the surface of specimens. Other solutions useful for
surface desinfection in hospitals are to be diluted by water. Using the
concentrated stuff may not be effective. I never tried their usefulness as
pyrite is not my main interest.

Tetracycline is known to form precipitates with cations like Ca2+. Maybe the
reaction with Fe2+/3+ is the reason for the black colour you observed. Just
an idea ...

Regards,
Jürgen
Ulm - Germany


R. Peter Richards schrieb:

> Thanks for the reference, Pete.  I've  heard of the bacterial
> mediation theory in the past, and read mixed opinions about how
> important it is.  Even tried treating a decaying pyritized ammonite
> with tetracycline once - it turned black but I'm not sure the
> treatment did any good....
>
> Pete Richards


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