Cleaning Barite off Amethyst

Any suggestions on how to clean Barite off Amethyst? Will Sulphuric Acid work?
Regards,
Jason

Mechanical is the only way to do it. Scrap it off with a knife or use a wire brush (dremel).

Reiner is right. There is no practical way to remove barite with chemicals. Unless the quartz you are removing it from are large and well defined crystals, the chances of removing it completely with a knife or use a wire brush (Dremel) is not likely to be completely successful. That is probably the best way to go for removing most of the barite, but you may not be able to completely remove it unless you have access to a micro abrasive tool using glass beads to detail the residual barite out of all the cracks and crevices. Even this is no guarantee to remove it all, but it will remove almost all of it.

Rock Currier
Crystals not pistols.

Hello!

Do you have any pics of the specimen?You should do it mechanically,but if you can avoid the abrasive machine.The pressure will make the Quartz internally cracked near the surface,some people say.

But we need to see the specimen.If you are talking about needle Quartz there is no way you end with a pristine specimen.

Good luck!
-Kostas.

If you're talking about T-Bay amethyst, be sure that it's a surface growth and not intergrown, or removal will leave scars that are as unsightly as the barite. In my experience, it's best to just avoid collecting the stuff.

T

Hi Jason,


If you want to clean amethyst of baryte there are two possibilities I know of:

1) Conversion of BaSO4 to Ba(HSO4)2 with hot sulfuric acid (that stuff is dangerous - hot and aggressive) - a rather slow process (and beware of fluorites...)

2) EDTA: You can dissolve BaSO4 in hot basic EDTA solution



The classic way of dissolving BaSO4 may not work for amethyst as the color may suffer from the heat

Soda-Pottash Method:

BaSO4 + Na2CO3 -> BaCO3 + Na2SO4

BaCO3 can be removed with acetic acid. You need to melt the potash in order to perform that reaction.

I hope that is of help.

Holger

It might be that you can remove it mechanically. Barite is soft compared to quartz and you can break off as much as you can with hand tools, and then clean up what is left and hard to remove with hand tools by use of an air abrasive tool. Ba rite is relatively soft and can be easily abraided away with glass beads. I would try that over trying to remove it chemically.

Rock Currier
Crystals not pistols.

> The classic way of dissolving BaSO4 may not work for amethyst as the color may suffer from the heat

No need to worry about the color of the amethyst - the molten soda will slowly dissolve the quartz :D

I'd try to do it mechanically, as Rock suggested, although quartz is brittle and easily damaged when you apply too much force.

As an aside, barite is so difficult to convert into soluble barium salts that in the processing of barite (and celestine) ore, the barite is actually heated with coke to convert it to barium sulfide, which can then be dissolved in water and acids, producing a barium salt and H2S. I found this out when dissolving a technical grade sample of strontium carbonate in hydrochloric acid: it smelled like rotten eggs due to residual sulfide getting turned into H2S!

As a chemist I would avoid chemical methods for attacking the barite. They are just too aggressive and dangerous. A mechanical method that is worth a try is to use a pressure washer and try and blast it off with a water jet. Barite is brittle, and with a well developed cleavage, it just might do it. I have had some limited success this way in getting barite off fluorite, only to find that the fluorite underneath had faint impressions of the overlying barite, and a poor lustre. Seems the fluorite had not quite finished growing when barite deposition began. This is the danger you might face with your amethyst. You get the barite off to discover poor quality amethyst underneath. Worth trying on a small piece first anyway. Good luck.