FMF - Friends of Minerals Forum, discussion and message board

[Mathias]

A few months ago I purchased this Fluorite specimen on a local mineral fair. The specimen's size is 8 cm. It came with a handwritten label. The specimen is totally OK, but the pink fluorite is covered by probably Chlorite. Can it be cleaned in some way?
The label says Chlorite inclusions but it is more a surface layer.

[lluis]

Hi, Mathias

Over the paper, it could be cleaned with hydrofluoric acid.
But it is extremely dangerous (I am chemist and I only fear this acid, and some carcinogenic items.... :-( ), and results could be worse than original (my sad experience with a Dalnegorsk' s piece (clean, but horrible....)).

I personally would suggest you to let it as is...

Same for the Monteponi piece (cleaning there, to me, is just polishing, which is a sacrilege....)

With best wishes

Lluís

[Jesse Fisher]

Chlorite is a silicate, and the only thing that will chemically remove silicates is hydrofluoric acid (HF). As Lluis mentioned, however, this stuff is incredibly toxic and should never be handled by anyone who does not have training in chemical safety procedures and access to a professional-level laboratory. Perhaps best would be to try and remove it with a physical method. Easiest would be to try a high pressure water gun. Failing that, an air abrasive unit with a soft powder such as plastic might work. Keep in mind that the surface of the fluorite under the coating might be pitted, so removing it may not improve the appearance of the specimen enough to be worth the effort.