Opal-Fluorite / Beryllium Nodules
My specialty. Opalized Fluorite: One of the most scarce, beautiful and unusual stones in the world, this stone only comes from one small area in the Utah west desert and is not open to the public for collecting. Try to find any of this exquisite gemstone and you'll know what I mean; it's not only very rare, it is very scarce. It is a soft opalized stone that forms in very small to 100+ pound "nodules", composed of predominantly opalized fluorite (blues and purples), often with many other minerals such as quartz, dolomite, rhodonite, manganese oxide, beryllium and other surprises. It often has a "crackled" appearance and is sometimes called "Tiffany Stone", or "Ice Cream Opalite". As long as there is blue/purple in the stone I call it Opal-Fluorite.  I love this stuff!

Mineralized nodules (commonly called "beryllium nodules") show stages of alteration by fluorine-rich mineralizing fluids. The nodules were originally clasts of carbonate rock, incorporated into the beryllium tuff during eruption. Carbonate rock fragments show the alteration sequence dolomite-calcite-chalcedonic quartz/opal-fluorite. The alteration sequence was deduced by studying the sequence of minerals in a group of zoned nodules, and by analyzing the trace element content of zones with a laser spectrograph.