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Author Topic: Opal in oil ?  (Read 679 times)

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Brucew

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Opal in oil ?
« on: March 01, 2017, 05:17:33 PM »

I just picked up several jars of various types of opal from an estate,  the seals on the jars are marked 1978.   The jars are all filled with oil,  judging by the smell I would say vegtable oil ( not good).  Is there a reason to put opal in oil as I have never seen or heard of it being done before,   Should opal be stored in water ?
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lapidaryrough

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Re: Opal in oil ?
« Reply #1 on: March 01, 2017, 05:21:14 PM »

opals are one part silica - one part water. the oil is to  prevent the material from drying out.
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Silicate life form

vitzitziltecpatl

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Re: Opal in oil ?
« Reply #2 on: March 01, 2017, 05:38:53 PM »

Once upon a time it was a common practice to store opal in oil. Now that's seen as not a good thing to do. Much has been written about it, but best practices are either store it in water, or store it dry so that it cracks wherever it will before you cut it into a nice cab.

Very nice that you could pick up some old-stock rough like that. Hope you'll post some photos.

hummingbirdstones

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Re: Opal in oil ?
« Reply #3 on: March 01, 2017, 06:03:34 PM »

Actually, most opal is 6% - 10% water, depending on where it came from and the depth is was dug at.  The percent of water can be higher, but that is more rare. 

https://en.wikipedia.org/wiki/Opal
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Robin

olgguy

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Re: Opal in oil ?
« Reply #4 on: March 01, 2017, 06:11:33 PM »

Back in the 1980's we used to store in glycerin to keep the air from drying out the Opal.
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finegemdesigns

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Re: Opal in oil ?
« Reply #5 on: September 11, 2017, 11:22:08 PM »

After you get them out of the oil (or water) it's a good idea to let them air dry for a few months to see if they are stable. If you sell an opal to a customer and it cracks a year from now your reputation will be damaged. Especially scary are Mexican opals while Australian are generally more stable overall.
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ASO

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Re: Opal in oil ?
« Reply #6 on: September 11, 2017, 11:42:42 PM »

Oil and glycerin were very common back in the day but not necessary and sometimes detrimental to the stones over a long period of time in my opinion.  Better off storing in water or just letting them sit in air with some humidity that way if they are going to ever crack you will find out before you cut it.  If a stone cracks just trim it and cut around the crack, if it crazes through it in the fish bowl.     
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