This piece of opal has a white body colour with predominate red play of colour, orange, green and blue secondary colours.
The bright gemmy stone is comparable to the best white opal from South Australia.
Hydrophane Opal is dry and porous and readily absorbs and loses water.
The photos above show the dry stone.
When immersed in water a very striking change occurs over half an hour or less.
Photo above shows the hydration zone surrounding the dry white area in the center.
At 7 minutes, the hydration progresses towards the center.
The hydrated opal becomes water clear.
Back of stone.
It is fascinating to watch the change.
On some of these Welo stones, the spectral colours disappear when the stone is hydrated.
Not this one!
At 10 minutes, the water has nearly reached the center.
12 minutes
At 15 minutes the stone is fully hydrated.
This has now become water clear, and is a magnificent clean gem.
The colour and movement in this stone is beyond words. Note the reflections of spectral colour projected onto the plastic base that the stone rests on in photo above.
Photos below show back of the stone.
Note the strong projected colour on my thumbnail
Within 20 minutes the stone returns to a white base as the water leaves the stone.
Over a period of hours to days, the stone regains it's original state, depending on humidity.
This stone weighs 7.15 carats dry- it is totally clean and sound.
This desert opal is from a large find of seam opal in a rhyolitic horizon - it is so new, that no one can say with any certainty what the stability is.
I know several cutters who began buying and cutting this material late in 2008 - so far there are no reports of crazing.
It is softer than Australian or Brasilian opal, this piece was quite robust when cutting wet- i rubbed this starting with a 320 hard wheel.
Read on to the end for a discussion of the material
I rubbed the rough clean up to 1200 mesh and left it overnight
same stones wet
as noted before the material is strongly hydrophane
variety of body coulours - material dry
material dry
material dry
rolling flash
some shots of the hydrated material
two pieces had fractures so i used pliers to snap them off
see the text below for a discussion of stress relief fracturing
here are the two chips from formation cracks- cutters!
September 11 update
some stones from the material above- 1200 mesh finish - my polish pad got contaminated :(
Here is some detailed email correspondence beteween me and Mike Kelly of Opalfire.info concerning the material, Mike has cut a lot of opal from origins outside of Australia and is well equipped to comment with decades of experience.
Thanks Mike for making the effort to share your experience with me in detail.
"
Hi James,
I have handled quite a bit of this stuff. Sure is pretty. I was not interested for quite a while, as I got a parcel back in the chocolate nodule days and it fell apart on me, all of it. But this new crystal opal is great. Weird, but nice colors, huh?
I haven't had much cracking problems. A few surface cracks which I ground out, and an occasional piece I've had to split open along the fault line. But it doesn't seem to spontaneously crack, the way LR crystal does to me sometimes. and I haven't seen any cracking after I've cut a piece. So I think it is pretty stable, esp after cutting and polishing. A lot of people are polishing 360 around on these, but I think a regular cabochon cut should be fine. So you can treat it pretty much as you would any crystal or white xtal body. The amber and darker shades of body tone are iron rich. That damps the fluorescence and lessens the hydrophane quality. So the darker ones could be treated like any opal. The lighter stuff of course is extremely hydrophane.
When you get it wet, the hydrophane property kicks in. The white body tone will clear, making the stone really show the internal color, but then the color fades to clear too and you have a piece if clear opal in your hands. The play of color and body tone will come back as it dries, which shouldn't take long there in the desert. Here, in a rainy Spring, it took a while.
So it would be good to plan and chart your cut, with notes and drawings if necessary, before you start cutting.
Or you can cut it just like you would cut any opal you have ever cut, but using water, It's gonna go clear on you.
I haven't had cracking problems once I get the surface cracks ground out. The rough is already so dry, you don't have to worry about it losing water and creating stresses. Several people have told me that you can wet it and dry it as much as you want and it won't create cracking.
I love the patterns in this material. I'm seeing lots of "almost" harlequin patterns, stairstep bars and lots of triangular forms.
My big question is value. Right now it is cheap, compared to Aussie material of the same or similar quality.
I'd be real interested to hear what you think about it, and how it is being viewed in LR circles "Mike "
"James: "
when rubbing the parcel i noticed a lot of the bigger nodules had formation cracks in them. NOT what i would call crazing, more like the "natural joins" seen in Lightning Ridge material which are often recemented with a subsequent opalisation event.
The piece shown on the top of this page has been wet and dry 100's of times, been out in the sun all day on a black iron frying pan ( winter here) , frozen in the freezer overnight and no cracks as yet.
Things are already pretty dire in the Australian opal mining scene- I think there are more buyers turning to mining to try and get some supply!
Most who are in it now are over 50- and not many young ones coming aboard.
I notice a bit of this material starting to come out of Chanthaburi and Bangkok, so i am assuming there will be a bit of continuity of supply.