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Generalhow to preserve a Mexican apophyllite / laumontite specimen

19th Feb 2018 21:20 UTCDon Windeler

Folks:

Back in 2008 I bought a nice specimen of pink apophyllite from Mina Sabinas, San Martin, Zacatecas. I recently dug it out as part of a cataloguing project and found that it's gone fragile on me; chunks along the edges are breaking off when I pick it up.

I'm pretty sure it's the laumontite dehydrating and decrepitating, as it makes up the majority of the matrix. There's a bit of chalcopyrite in there, but it's a couple of crystals rather than anything integral.

Here's a crummy snapshot of the specimen, about 9 cm in longest dimension:

Assuming I'm correct about the laumontite, does anyone suggestions about stabilizing the piece? I know there are California laumontites that are soaked in some kind of white glue mixture to preserve them, but don't know what proportions or process makes the most sense.

Any tips, or am I destined to be sharing a big pile of pink apophyllite thumbnails?

Cheers,

D.

19th Feb 2018 22:16 UTCBecky Coulson 🌟 Expert

Don, I have two large specimens of Laumontite - one from the Deccan traps of India, one from the Isle of Mull, Scotland that I collected. One is 10 years old, the other over 20.

I bought a fixative spray (Krylon) used by artists to seal charcoal drawings, and sprayed both with repeated applications to avoid dripping but ensure coverage. Both specimens appear stable, and there has been no discoloration. The smell of the spray disappears after being aired for a few days.

I don't know how well this will work if decomposition has already begun.

19th Feb 2018 22:26 UTCGeorg Graf

Hi Don,

found in 1984 Laumontite on the Faroe Islands, starting to decompose in some days in the room. I put 2 spezimens in a box filled up with water. They are ok still today. Don´t know, what happens with water, in case decomposition has already started.

Kind regards, Georg

20th Feb 2018 10:48 UTCKeith Compton 🌟 Manager

Hi

I have found that in addition to artist fixatives, hairspray also works. But you should also then keep it dust free.

If the Laumontite has started going on you in serious way, it may be too late anyway.

In my experience preservatives need to be added to Laumontite early on - they are a preventative measure not a cure.

Cheers

20th Feb 2018 12:58 UTCChris Rayburn

Don,

I’ve had good results stabilizing specimens with a solution of one part Elmer’s glue and two parts water. I generally apply it to the back side of the specimen using the glue bottle as a dispenser. I’ve also placed specimens face-up on a piece of screen and dipped them into a small container of the solution. It does not affect the color or luster of specimens in my experience. You must take care handling the specimen before it’s dried, as wetting can cause the matrix to soften. I generally let specimens dry (cure) on a sheet of aluminum foil, and gently move them every 30 min or so such that they don’t adhere to the foil. It’s best to test this technique on a lesser specimen(s) before your keepers; unfortunately it doesn’t sound like you have this option…?

I should add that I haven't tried this technique on laumontite.

Best of luck,

Chris

21st Feb 2018 05:09 UTCDon Windeler

Thank you all for the commentary. As surmised, I don't have the luxury of pre-emptive strikes here; when I bought the piece I was completely unaware that laumontite misbehaved this way. All I can do right now is reinforce the piece, unless there's some magical means of rehdrating the laumontite matrix. (Not so likely...)

I think I will try the white glue approach in the hope that it will make it sturdier. Don't think I have a lot of other options, as every time I move it it's crumbling more.

Appreciate the suggestions -- if any more come to mind I'll try to onboard them before the glue dunking!

Cheers,

D.

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