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Post by Toad on Oct 16, 2009 8:48:22 GMT -5
Has anyone ever tumbled this, or is it as delicate as precious opal. Looks like it would be hard enough, and expense probably isn't an issue. But maybe as the slurry heats up, the water would be driven out - causing fracturing. Appreciate any thoughts.
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Oct 16, 2009 10:14:43 GMT -5
Water and opals in general do not do real well together, with that said, some common opals will survive tumbling and come out kind of nice, but far more will either lose too much material and keep chipping or cracking through the tumbling stages, while much or the opal from Oregon or Nevada will simply fall to tiny pieces.
I have only had limited tumbling success with pink and blue common opals from Peru, and sometimes Spencer opal from Idaho, but Spencer isn't very exciting since its just white with color layers almost microscopically thin and hard to see- and really I've had no luck with any others.
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Post by Toad on Oct 16, 2009 10:48:22 GMT -5
Hmmm, that doesn't sound promising.. But I suspected as much. Thanks for the reply.
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Post by akansan on Oct 16, 2009 12:19:35 GMT -5
I think it was Jonje that tumbled blue opal - turned out lovely. It's a softer stone, but it does take a polish in a tumbler.
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Post by rocklicker on Oct 16, 2009 16:40:33 GMT -5
I was about to try some. I got some opal chips to tumble. I'm thinking to start them out on 600 grit and keep recharging until they are ready for prepolish and polish checking often. I was wondering about the water and heat issue too. Maybe better to tumble them during the winter months.
Steve
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Oct 16, 2009 18:58:06 GMT -5
I don't think the "heat" of tumbling is going to draw water out- in fact I expect opals in a tumbler are as likely to absorb water more than lose it, but any changes in either direction to the hydrological balance in the structure of an opal can lead to crazing and disintegration.
Starting with known stable stuff is essential, monitoring on a regular basis is also crucial, with the right material you can get some nice results, but there is always that risk...
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Post by Toad on Oct 17, 2009 9:23:27 GMT -5
Well, if I happen to come across solid looking material at the right price, I'll give it a try - if not, there is plenty of other rocks to tumble.
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