cleaning Smithsonite from Greece?

I have large Smithsonite from Laurem Greece with a orange stain on it how
do i get it off,ultrasonic,acid,high pressuare water gun?thanks

Hi Jonathan,

If the orange stain you mention looks like this [www.mindat.org] [www.mindat.org] [www.mindat.org] then it is caused by a thin layer of iron oxides. It will be difficult to remove it without ruining the silky luster of the Smithsonite (don't try any acids!). Also, it is very probable that it's not just a surface stain, but penetrates within the Smithsonite, in which case you can not remove it. Still, I would strongly suggest NOT to remove it...i certainly wouldn't, this is a beautiful and distinctive form of Smithsonite from Lavrion.

If it looks like this [www.mindat.org] then you have a rare "cadmium smithsonite", with the yellow color caused by minute Greenockite inclusions. This, of course, can't be removed. And why would you try to remove it, it's a rare and desirable habit!

Lefteris.

thanks i will not try acids,my smithsonite looks like the picture but is med blue and it
weighs 1148 grams,it is old timer i got label from paris from 1890 or early,i may put
back in ultrasonic the mineral is 5inchs by 4 by 2 thanks Jon.

Jonathan,
Can you supply an image of the specimen?
The first step it to look at the orange stain under a microscope or magnification and probe at it with a needle and to determine if it is on the surface of the smithsonite on actually included in the smithsonite. It it is the latter, there is not much you can do about it. If it is just on the surface and is an "iron" stain you can probably remove it with a Waller solution. Its use in cleaning quartz is described in the article on cleaning quartz [www.mindat.org].

Rock Currier
Crystals not pistols.

Why is it that you know the specimen is "an old timer from Paris"? If this is because of an attached label (such as an A. E. Foote label), then cleaning the specimen may damage or destroy the attached label. An attached label of this nature adds significant value to the specimen, so maybe better to not clean it at all.

Not having seen the specimen yet, I have a feeling it should better be left in the same state it has been since 1890...!

Lefteris.

The label is Alex Stuer and it is not attached to the mineral thanks for the help,i think the stain is rusty limonite?jon