I guess this would qualify as a unique rock type.
But like everything else about this stone, it depends on who you're talking to.
Tiffany Stone, or Bertrandite, is also sometimes called "Purple Opal" and "Ice Cream Opalite"
Bertrandite Opal Tiffany Stone would be a good all inclusive name for the material,
but let's just call it "Bert" for short.
Seams of Bert have only been found in the Brush Wellman beryllium mines
located in the Sevier Desert of the Topaz-Spor Mountains of western Utah.
Occasionally some of this material escapes the crusher and makes it way to the surface.
The Bertrandite is the creamy white areas, and the purples and blues are fluorite.
The black lines are mostly Manganese.
Also in the mix are Chalcedony, Dolomite, and Rhodonite.
But the "whole mess" is said to be "opalized".
There you have it.
I have been cutting some Bert rough lately to have some slabs for Grassy Creek!