All, I recently saw a cut stone on a site that was called Bertionite, aka Tiffany Stone. I have some of that material and have cut a number of stones but was always under the impression that it was a massive opal material from some deep mines in Utah.
Couldn’t find it in the GIA Gem Reference Guide, and it wasn’t on a
couple of old misnomer lists, nor in Sinkankas’ Gemstones of North
America, so maybe bertionite is a local name. I did come up with a
few related images:
Jackie Lapin has some spheres of what’s called ‘ice cream opalite or
Tiffany Stone’ from Utah at her site.
One metaphysical site calls it ‘opalized fluorite’ and there’s a photo
with that name on an old eBay auction
Checking the Utah Geological Survey site with Slides of the
Fluorspar, Beryllium, and Uranium Deposits at the Spor Mountain,
Utah, found a slide of fluorite encrusted opal:
Don’t know if it’s the same as your material, but I had an interestng
time looking for it! Carol
Carol J. Bova