Opal soaked in glycerin

Jewelry Discussion
1

Along with my late father’s lapidary equipment and supplies, I
inherited several small jars and vials of opals in liquid. I think
it’s Coober Pedy opal–it’s all white with lines of fire here and
there. I recently got a book on opal cutting by Paul B. Downing, and
went into the jars for the first time to get some out for practice. I
thought the jars were filled with water. But it seems that the opal
has been stored in glycerin for 30+ years.

I took three small pieces out and rinsed them with water to remove
the brownish floating gunk that had accumulated as the glycerin
separated (or maybe spoiled?). As soon as they dried they began to
look very chalky on the surfaces.

Here’s the question: I’ve never seen rough opal that wasn’t in a jar
of liquid… is that chalky look normal for rough opal, or did
soaking in glycerin for 30 years damage the stones?

I haven’t tried polishing anything yet–I want to finish the book
first. ;')

Kathy Johnson
Feathered Gems Jewelry
http://www.fgemz.com

2

Along with my late father’s lapidary equipment and supplies, I
inherited several small jars and vials of opals in liquid. I think
it’s Coober Pedy opal–it’s all white with lines of fire here and
there. I recently got a book on opal cutting by Paul B. Downing, and
went into the jars for the first time to get some out for practice. I
thought the jars were filled with water. But it seems that the opal
has been stored in glycerin for 30+ years.

I took three small pieces out and rinsed them with water to remove
the brownish floating gunk that had accumulated as the glycerin
separated (or maybe spoiled?). As soon as they dried they began to
look very chalky on the surfaces.

Here’s the question: I’ve never seen rough opal that wasn’t in a jar
of liquid… is that chalky look normal for rough opal, or did
soaking in glycerin for 30 years damage the stones?

I haven’t tried polishing anything yet–I want to finish the book
first. ;')

Kathy Johnson
Feathered Gems Jewelry
http://www.fgemz.com

3

The reason for glycerin is that glycerin will conceal any fractures
in opal because of the refractive index.

KPK

4

Kathy,

opal can look chalky on the surface, in Coober Pedy it is often
associated with gypsum and calcite and the non fiery opal has a dusty
ook to it. The prolonged soak in glycerin will not have done the opal
any good but it may not have harmed it too much. I would suggest a
soak in distilled water in a glass vessel for a couple of weeks to
get rid of the ingrained glycerin though. After that leave a piece to
air dry for a couple of days and see if it looks OK or if it looks
crizzled. If the latter, you will have problems and you can hope that
cutting away the exterior produces a more stable stone.

nick

5

Kathy

As I’m sure someone has already pointed out, you have Hydrophane, at
least the pieces you washed were hydrophane. Hydrophane is a chalky
form of Opal that only has fire when it’s wet. As far as I know there
isn’t a way to capture the fire unless it is in water or some-such
medium. Best thing to do with them is to just change the liquid and
maybe the jars. Add a drop of bleach to the water, or Grape Seed
Extract to prevent biological entities from living and multiplying in
the medium and consider the opals to be eye-candy.

However, not all of those pieces may be hydrophane. Dry it all out.
Put it all in a plastic zip bags wrapped with wet cloth or wet paper
towel and let it dry for A FEW YEARS! Don’t worry, the Hydrophane
will not be damaged. Once the Hydrophane reaches water again it
will, after a short time, return. Everything that does not crack or
become chalky might be cuttable. I say “might” because I don’t really
trust anything from Coober Pedy to be stable. I don’t cut them any
more having cut a few thousand dollars worth of garbage.

TL Goodwin
Lapidary/Metalsmith
http://thepacifikimagestore.com

6

Hi Todd,

I don't really trust anything from Coober Pedy to be stable. I
don't cut them any more having cut a few thousand dollars worth of
garbage.

Oh dear! Does that apply to cut stones too or just rough? I recently
bought some beautiful Australian opals - some Lightning Ridge and
some Coober Pedy. They are gorgeous and I have plans of how I want to
set them. I’m hoping that they’re not going to start crazing on me!

Helen
UK

7

Helen,

Generally Cooper Pedy opal is quite stable, I have some that has been
out of the ground for decades now with no sign of crazing or other
deterioration. There are some opals (Mexican jelly opal comes to
mind) that are unstable as mined, as is Ethiopian opal, but to my
knowledge Lightning Ridge and Copper Pedy opals (the good quality
gem grade stuff, potch can be a different story) are very stable.

Cheers, Thomas Janstrom.
Little Gems.
http://tjlittlegems.com

8

Kathy,

The glycerine is not good for storing opals that will be cut. It is
hydrophilic (pulls water out of the opal), and makes the opal
structure less stable, and prone to cracking or crazing.

The chalky white could be potch which would normally be trimmed or
ground off, or it could be hydrophane opal as someone mentioned,
which only shows color and translucency when it’s wet. Or it could be
something that precipitated on the opal as it dried out. It will be
obvious once you start cutting which is the case.

Since the jars are 30 years old, the floating brownish gunk could be
rusty flakes from the lids of the jars deteriorating over time and
not be related to the opals at all.

Unfortunately, the glycerine may have damaged the opals. But you
have nothing to lose in using them for practice. If they survived the
glycerine, and survive cutting without cracking up, then you’ll
still need to let them sit for several months to a couple of years to
see what happens.

Overall, if it’s not mistreated, some Coober Pedy is stable and cuts
well; some is not stable and will craze. The depth at which it’s
mined may be a major factor, but there’s no way of telling now with
yours, except by cutting and watching.

You can go to the American Opal Society website, www.opalsociety.org
for a low-tech way to polish opals using wet/dry sandpaper on dowels
or wood blocks. Tim and Barbara Thomas have some common sense,
straight talk opal FAQs, and a guide to cutting opal on their
website, http://www.opal-tibara.com/ They also have photographs of
several types of Coober Pedy opal so you can see the wide variety
that is available.

Now, with all this bad news about your opal rough probably being
unstable, you can still clean it up, and if there’s color, put the
little bits that fall apart into little sealed vials filled
with…glycerin or mineral oil. They will reside there quite happily
as long as their container is sealed as a display item, or the tiny
vials, can be used as pendants.

Carol
Carol J. Bova

9

Correction

I should have not sounded so definitive. I should have said “it
sounds like you may have Hydrophane”.

Without seeing the material my self, it’s hard to identify for sure
on a verbal description.

TL Goodwin
Lapidary/Metalsmith

http://thepacifikimagestore.com

10

Hi Helen

Sorry to take so long to get back to you. It’s iffy with any opal I
think. I had opal I cur from rough from one dealer survive 98 deg
Fahrenheit direct sun in a glass case for three days without a
problem. It had come from a jar of Coober Pedy material that was in
water. I bought some jars from another dealer who told me the
material had been dry for years prior to being put in water, and the
only reason it was in water was to show the fire. Those all cracked
without any special mistreatment, days, months, and a few years
later. I should have done nothing with them for a few years before
cutting them.

I found some cracked just the other day. Ugh!

So, I do still cut opal and I will in the future, I’m sure. I’m not
going to seek out Jars of Coober Pedy rough anymore, unless I find
the dealer who sold me my original jars again.

I was looking at a book on Theodore Farner’s work. In that book were
some very crazed opals.

I just can’t trust them.

It’s possible the gems you bought might last. I still own the ones
that were exposed to three days of desert sun under glass. That was
11 years ago. They are fine!

Sincerely
TL Goodwin
Lapidary/Metalsmith

http://thepacifikimagestore.com