FMF - Friends of Minerals Forum, discussion and message board

[geoalfon]

Hi everyone, recently I have obtained some pyrite suns from Illinois directly obtained from the mine. They are dirty. I have read that water is very bad for this kind of material.

How can clean them?

Thanks a lot
Best regards
Alfonso

[lluis]

Hi, Alfonso

That water is not good, one could imagine (small crystal, easier to be altered....).
Then, I think that only way would be an abrasion treatment, with a not-too-hard dust, like could be nut shell dust (I have read that used in USA...No idea where could be had in Spain....)

Or maybe you could try with a brass cleaner (in Spain, I think is Mistol), and then dry with alcohol and rests wiped out with a pencil....

If you mail me private, maybe we could talk more.
Only not to disturb listizens to the point to hate me... :-)

With best wishes

Lluís

[Carles Millan]

[Trudy Bolin]

If the pyrite was in a mine, then it was probably already exposed to water. It looks like there's dried mud on the surface.

If the pyrite has managed to be stable up to this point, then it probably won't react with the water used for cleaning. Some specimens of pyrite (and marcasite) do undergo decay, but many times by the time we get to them they are already showing the signs. But not always, and I'd hate to see your suns go south, so to speak.

You should encase them and try to control the environment they are stored in. If pyrite is going to decay, then heat and humidity will play a role.

Just a thought.

[Joseph DOliveira]

I have cleaned many of these pyrite/marcasite suns over the years. The material that is stuck on them is shale from the formation that they form in. I use a small table top sand blaster with glass beads. The pyrite has a hardness of 6-6.5 and the glass beads are around 5-5.5, so they don't damage the pyrite suns.

If you don't have your own sandblaster, try an automotive repair shop to see if they will give you access to their blaster, they use it for cleaning parts. I used this method for my initial attempt at cleaning them, for the price of 12 bottles of beer, I was able to clean my entire batch of specimens, I later purchased my own blaster as I required it more frequently.

[geoalfon]

Thanks a lot for the replys.
Lluis I will send you a private.
I have some samples, I will try with Cillit Bang.
About the sand blaster I have not got one, but one friend of mine has got. I will give to him one sample for clean it.

Best regards
Alfonso

[Les Presmyk]

If you are going to use an abrasion unit start with the softest medium (blasting agent) and lowest pressure possible.

Also, just because pyrite or marcasite may have been subject to wet conditions when they were collected does not mean they are immune from the effects of water at a later date. I have had these pyrite suns fall apart after washing in water because I did not dry them with alcohol or acetone. If you are going to use liquids, I would start with rubbing alcohol. This will help remove the clays without harming the pyrite.