Joined: Fri Feb 24, 2006 1:20 am Posts: 2756 Location: Southern California, U.S.A.
I made my debut in the 1990s. Don’t judge me too quickly – I may not be what you think. Keep in mind that I’m a lightweight. I love warm weather: Tanzania suits me fine. I wear many fine colors but they’re not as fancy as my uppity cousins. Who am I?
The name of your thread makes me think faux or imitation. I was thinking fiber optic glass cats eye but, can't associate it with the geography or warm weather. Lightweight makes me think plastic.
Are those little spheres in the stone gas bubbles?
Nevermind, don't answer. I need to think this through.
Joined: Fri Feb 24, 2006 1:20 am Posts: 2756 Location: Southern California, U.S.A.
JB wrote:
Sorry Rom, Tanzanian fire opal is an e-bay nomenclature.
Opal has been found in Tanzania though, and some opal can be chatoyant.
Now I'm really stumped.
I'm calling you the winner JB, for nailing the Tanzanian and chatoyant aspects. Congratulations!
In the opal trade 'fire opal' has a very specific meaning. It refers to the yellow-orange-red transparent opal found in Mexico and a few other places like Washington State and Brazil. It usually exhibits no play of spectral colors. It's almost always faceted, not cabbed.
Chatoyant or cat's-eye opal like the stone illustrated comes from Tanzania. (I've also heard of cat's-eye opal from Brazil but don't know if it's the same as the Tanzanian). It occurs in quite a few base colors, from black to pure white as well as a range of brown, brownish-red, yellow, silvery etc. -- but the colors are nothing like its showy precious opal 'cousins' from Australia, and Brazil. Quite a few cat's-eye opals are currently on the market and gemologists might encounter them set in jewelry.
Opal is amorphous in structure (no crystal form) and is a secondary mineral. It fills cracks and gaps and is often a replacement for fossil wood, bones, clams and belemnites, etc. In this case common opal or opalite has apparently replaced some fibrous mineral like asbestos. Enough of the fibrous structure is retained in the opal to allow cat's-eyes to be cut.
Joined: Fri Feb 24, 2006 1:20 am Posts: 2756 Location: Southern California, U.S.A.
JB wrote:
You are good ROM, REALLY good and well studied.
Keep em coming. It's like an advanced gemology course.
We're soaking it in.
I'm blushing. Thank you -- I'll bask in all that praise until the next time I screw up!
I'm thinking of a couple more quiz possibilities but will have to ponder them for a while. Meanwhile, have a safe and happy holiday all you Yankee Doodle types, and a great weekend wherever the rest you are!
Here's a cat's eye opal I got from Thaigem a couple of years ago, along with some boulder opal, all from Colorado. It's in the brown shades with gold and silver tones, and the eye opens and closes. You can see where the second line starts but I couldn't capture a good image of it open.
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