Typically colorless with a “sleepy” look, cryolite is rarely found in nature. Rough suitable for gem faceting is extremely scarce. However, the synthetic version of this mineral has many industrial uses.
Weak thermoluminescence. Some specimens may fluoresce intense yellow under shortwave UV, with yellow phosphorescence, and pale yellow fluorescence under longwave UV. Specimens from Mont Saint-Hilaire, Canada may fluoresce pale blueish white under shortwave UV.
From the Greek kryos, “frost,” and lithos, “stone,” hence “ice stone,” in allusion to its appearance.
Occurrence
Occurs in alkalic rocks, granite pegmatites.
Cryolite crystals with minor brown siderite patches. Ivigtut Mine, Arsuk Fjord, Sermersooq, Greenland. Photo by Kelly Nash. Licensed under CC By 3.0.
What is Cryolite?
The mineral cryolite has been used in the aluminum industry, first as an ore itself and then as a flux to extract aluminum from other ores more efficiently. Cryolite has proven to have many other industrial uses, from ceramics to pesticides. However, most of the material used today is synthetic.
Glassmakers can add cryolite to glass to create an opaque, white color. So-called “cryolite glass,” invented in Germany in 1835, proved very popular as a material for prosthetic eyes because of the naturalistic results. Cryolite glass eyes in presentation case, made in Lauscha, Thuringia, Germany, ca 1900. Photo courtesy of liveauctioneers.com and Auction Team Breker.
With a hardness of just 2.5 on the Mohs scale, cryolites would make a very impractical choice for jewelry wear. A copper coin (hardness of 3) could accidentally scratch it. Household dust, a far more pervasive hazard, has a hardness of 7 and can easily leave scratches on cryolites.
Typically colorless and very rarely transparent, cryolites seldom attract the attention of adventurous faceters or curious gemstone enthusiasts. You’re more likely to find cryolites, faceted or in natural forms, in a mineral or rare gem collection than a jewelry collection.
What’s the Difference Between Cryolite and Chiolite?
Cryolite, the “ice stone,” and chiolite, the “snow stone,” can appear very similar. They also occur in the same locations and have many gemological properties that differ only slightly. Both are rarely faceted, but chiolite is a rarer mineral.
Chiolite is a harder material (3.5 to 4), but scratch testing on finished gems isn’t recommended. Conduct this test only as a last resort for identification.
Since abundant sources of natural cryolites are very scarce, scientists have synthesized this mineral for a wide variety of uses. However, there’s no known jewelry use for this lab-created material. Cryolite’s softness and limited visual appeal make a viable jewelry market for synthetics very improbable.
Lapidaries could cut large cabochons from abundant material, such as what Greenland produced. However, facetable rough is quite rare and will only yield tiny gems.
How to Care for Cryolites
Clean cryolites with a soft brush, mild detergent, and warm water. However, please note that cryolites are slightly soluble in water. Don’t submerge these gems in water. After cleaning, carefully pat them dry. (Don’t wipe them dry). For more care recommendations, consult our gemstone jewelry care guide.
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