Tiffany Stone is a rare and unusual "opalized" (agatized) mineraloid that formed in mineralized nodules called "beryllium nodules."

Tiffany Stone is composed of varying combinations of minerals such as bertrandite (beryllium silicate), beryl, calcite, chalcedony, cobalt, dolomite, fluorite, manganese oxide, rhodonite, quartz and zinc. The purple color that characterizes Tiffany Stone was created by fluorine gases, while the distinct black-colored veins were caused by manganese oxide; all of which were sealed within the sedimentary layers, becoming opalized over time.

Opalized fluorite is a mineraloid which is a combination of amorphous hydrated, fluorine-rich mineralized fluids and silica-rich sediments. Amorphous materials where naturally created by the rapidly cooling molten material, and the rapid cooling process slowed and suspended the material's molecules before they could pack into a tight crystalline structure. The opalized fluorite formed in Irregular veins and nodules which were originally clasts of carbonate rock, incorporated into the beryllium tuff during eruption.

The rareness of Tiffany Stone comes from the fact that to date, the only location it has been found is at the Brush Wellman beryllium mine in the Topaz-Spor Mountains of Juab County's Sevier Desert, in western Utah. Beryllium (Be) is a light-weight, high-strength yet brittle alkaline earth metal which is used in structural materials for aircraft, missiles, communication satellites and space vehicles. Adding to the scarcity is the fact that the extraction process for beryllium involved crushing large quantities of material which yield only 1 to 2 percent of the concentrated ore. This remote mine is now closed to the public.