Noo.... fire opals are not girasols. Fire opals are from Mexico with a 5.5 hardness. I'm pretty sure 'girasol' anything is 7 hardness.
That confusion could cost someone a LOT of money if they were tumbling. If you throw even fire opals in with agates, you are going to lose a lot of fire opals. If you aren't paying attention to the loss, by the end of the first week, every single fire opal you put in might be powderized, leaving you with no opals at all.
Also, you CANNOT put opals in a rotary tumbler. While I haven't tried this, everything I've read says you cannot, and I'd imagine at some point the advice came from someone who destroyed their opals.
While opals are not the most expensive gemstones by a mile, some can still be considered precious gems, and the top graded could command as much as $75 per carat, which is 1/5 of a gram, or $375 per gram, or $375,000 per kilo (2.2 lbs).
Of course, no one in their right mind tumbles half a million dollars worth of opals without knowing what they are doing, but you do have to be careful saying it in case someone thinks of it as a fast easy way of cleaning and polishing (like me).
I DID throw 1/2 a pound of precious gem opals into my tumbler as a first batch, all with real fire, and some with top grade fire, because I realized HOW LONG it would take to clean and polish them one at a time.
Note, MY opals weren't the $75 per carat variety, but they are definitely of the $1-$5 per carat variety. Even at $1, 1/2 a pound is $1240, so yes, I threw over a thousand dollars into my tumbler first batch and took a $600 cash loss for trying it. And try to make light of it because I am not going to get either the opals or the money back. Of course I would rather buy a saw or grinder with the money than let my tumbler eat it.
I post this because I think anyone thinking of tumbling opals needs to read it, and do a whole lot of research before taking the kind of loss I did. DO NOT TUMBLE OPALS WITH AGATES.
I can't fathom why anyone started calling quartzes opals. That just makes no sense at all, and in a situation like tumbling, can lead to their destruction if you just toss them in with harder rocks.
