A Tiffany Stone nodule, sliced in half and polished. Can you see why some people call it "ice cream stone"? Public domain image by Scott Horvath, USGS.
What Is Tiffany Stone?
"Tiffany stone" is a trade name used for a purple, blue and white gem material that can be cut and polished into beautiful beads, cabochons and tumbled stones. Geologically, Tiffany stone is a rock composed primarily of fluorite with smaller amounts of opal, calcite, dolomite, quartz, chalcedony, bertrandite and other materials. Other names used for Tiffany stone are "opalized fluorite," "ice cream stone," and "bertrandite."
Utah Tiffany Stone: "Tiffany Stone" is an unusual material found as mineralized nodules in a beryllium tuff at the site of the Brush-Wellman beryllium mine. It is thought to be an opalized fluorite. Tiffany Stone is also known as "bertrandite" and "ice cream opal." It is a rare material found only at the Brush-Wellman location.
Where Is Tiffany Stone Found?
Tiffany stone is a rare material. It is mined at one location worldwide - the Brush Wellman beryllium mine, at Spor Mountain, western Utah. It occurs there as nodules that are part of the ore produced at the mine. The nodules typically contain between one and two percent beryllium by weight.
The United States Geological Survey reports that the nodules are carbonate clasts that have been largely replaced by fluorite. Small amounts of bertrandite, a beryllium mineral with a chemical composition of Be4Si2O7(OH)2, occurs as submicroscopic grains within the fluorite.
Almost all of the Tiffany stone mined at Spor Mountain is crushed and used to produce beryllium. A small amount has been carried out of the mine by employees, and a small amount has been gathered by collectors who have rarely been allowed into the mine. These are the only sources of the gem material because Brush Wellman has always been interested in producing beryllium and has not been interested in Tiffany stone.
Other Names for Tiffany Stone
The most appropriate name for Tiffany stone is “opal fluorite” or “opalized fluorite.” These names reasonably represent the composition of most specimens. Another popular name is “bertrandite.” That name is incorrect because bertrandite is a mineral, which only comprises a few percent of the rock known as Tiffany stone. It is also called "ice cream stone" because of its delicious color.
There are numerous stories behind the name “Tiffany Stone.” Some people attribute the name to Tiffany and Company, the famous luxury goods retailer. The company has never been associated with the mine or with Tiffany stone. Others attribute the name to the daughter of a Brush Wellman employee who collected the colorful nodules brought home by her father. This story is possible, but the names of the miner or his daughter are not found in any written record.
Where Can You Buy Tiffany Stone?
Jewelry made with Tiffany stone is unlikely to be found in a mall jewelry store. Instead, it is most likely to be sold at a gem and mineral show, at a rock shop, or by a lapidarist at a craft show. You might also find it at an online craft marketplace such as Etsy. Some of these sellers are likely to be the same person who cut the stone and made the setting. You will rarely find that when buying diamonds, emeralds, rubies or sapphires!
About Using Tiffany Stone in Jewelry
Although Tiffany Stone can be very attractive, there is an important thing to consider when using in jewelry - it has a Mohs hardness of only 5 to 5 1/2. That makes it very easy to scratch. If Tiffany Stone is used in a ring, it will quickly show signs of wear and lose its nice polish and luster. For that reason, Tiffany Stone is best used in pendants, beads, earrings and other types of jewelry that will not be subjected to abrasion.
One thing about Tiffany Stone that will probably make you happy is its price. Even though it is very rare and quite beautiful, cabochons with beautiful color, pattern and size can usually be purchased for $75 or less. It also looks great in white metal. That allows it to be placed in a sterling silver setting, getting you the whole piece for a price of $150 or less.