Etch-All Shatters Stone Beads!

[Luann Udell]

I went for an attention-grabbing subject line.   

Except that it's kinda true.  I went to a bead and gem show last weekend.  Yesterday, I took some of the stone beads I bought--smooth rock crystal nuggets and small smooth apatite nuggets and put them in a solution of Etch-All.

I promptly forgot about it til this afternoon.  However, I wasn't too worried because I know stones take a lot longer to matte than glass beads.

To my surprise, almost all the apatite beads had fallen apart!  I can actually squeeze the remaining beads between my fingers and they fall apart.  One or two of the rock crystal beads split and parted a long a 'fault line'.

Is this because I left them in a liquid too long (like an opal)?  Or because of the Etch-All? 

Actually, it makes me feel a little like Superwoman, to be able to pull rocks apart.  But I'm glad I only tried a few dozen beads in the solution.

[RitaD]

Were the beads "cracked" crystal or apatite?  I'm wondering if a previous heat treatment might have made them more porous or something...

[Russ Nobbs]

Probably because of the chemical reaction with th4 Etch-All, Luann.

Your question led me to a google search for "apatite mineral" so I could read about the mineral itself instead of all sorts of things made with apatite.
At http://www.galleries.com/minerals/phosphat/apatite/apatite.htm  I learned that "Apatite is actually three different minerals depending on the predominance of either fluorine, chlorine or the hydroxyl group. These ions can freely substitute in the crystal lattice and all three are usually present in every specimen although some specimens have been close to 100% in one or the other. The rather non-inventive names of these minerals are Fluorapatite, Chlorapatite and Hydroxylapatite. The three are usually considered together due to the difficulty in distinguishing them in hand samples using ordinary methods. "

Apatite is a  Calcium (Fluoro, Chloro, Hydroxyl) Phosphate (Ca5 (OH,F,Cl) (PO4)3.
I don't remember exactly the chemistry of Etch-All but it is mild glass solvent, probably made with ammonium bifluoride which makes hydrofluoric acid when dissolved in water. I suspect the hydrofluoric acid reacted with the calcium phosphate  portion of the apatite and dissolved part of the mineral. The reaction could be potentially hazardous, releasing fluorine and chlorine in gas form. (NOTE: this is a GUESS based on chemistry learned 50 years ago.)

Thanks for another interesting question!!!!!

[Luann Udell]

WOW!!!!  Thanks for the chemistry lesson, Russ, and the warning.  Um, our kitchen is in a state of...shall we say 'gentle dishabille'...?  I'm sure anything stinky would have been attributed to garbage.  (With the French pronunciation of 'gahr-bahzh'...)   

Will be careful not to etch any more apatite, for sure.

[daverobertson]

I'm sorry this made you lose your apatite, Luann 

[Polly]

Oh. Bad Dave. Bad.

    

[Russ Nobbs]

<sheesh> How did I miss that opportunity?

[Luann Udell]

Most excellent, Dave.   

[briensmith]

Etching on metal for jewelry design is a somewhat messy process, but it is well worth the trouble. Etching allows the artist to produce original hand drawn designs on the metal or to use premade stamps. The joy of learning to etch comes in viewing the finished product. I am usually surprised by the results, often thinking that nothing has happened until I clean and polish the metal. Below is a photo of three etched bracelets. The design for the one on the far left was hand drawn while the other two were stamped.

Thanks

spam link deleted by moderator (it didn't go to the description above - instead it went to unrelated beads)

[Russ Nobbs]

This helpful sounding post by a shill for Panda Hall was copied in full from http://www.magpiegemstones.com/copper_etching.html.

If you are trying to publish posts that are useful or helpful so it will not be removed by administrators, please write your own material and give credit for your sources.