An unusually large, faceted parisite, 6.40 cts, 13 x 8 x 6.5 mm, Pakistan. Photo courtesy of liveauctioneers.com and Jasper52.
More well-known as rare inclusions in emeralds, parisite crystals are usually small and seldom faceted.
An unusually large, faceted parisite, 6.40 cts, 13 x 8 x 6.5 mm, Pakistan. Photo courtesy of liveauctioneers.com and Jasper52.
More well-known as rare inclusions in emeralds, parisite crystals are usually small and seldom faceted.
| Data | Value |
|---|---|
| Name | Parisite |
| Formula | Ca(Nd,Ce,La)2(CO3)3F2 |
| Colors | Brownish yellow, yellow-brown, brown, grayish yellow, red, black, orange, colorless |
| Fracture | Subconchoidal to splintery |
| Hardness | 4.5 |
| Cleavage | Distinct basal parting or cleavage; perhaps due to alteration |
| Crystallography | Monoclinic (pseudo-hexagonal); crystals double hexagonal pyramids, often steep, sometimes prismatic, striated; sometimes rhombohedral. |
| Refractive Index | 1.668-1.772 |
| Birefringence | 0.081-0.104 |
| Luminescence | None |
| Luminescence Present | No |
| Absorption Spectrum | Rare-earth element spectrum |
| Pleochroism | Weak |
| Optics | o = 1.668-1.676; e = 1.757-1.772. Uniaxial (+). |
| Optic Sign | Uniaxial + |
| Luster | Vitreous to resinous; pearly on basal cleavage surfaces. |
| Specific Gravity | 4.33-4.42 (Malawi specimens: 3.97) |
| Transparency | Opaque, translucent, or transparent. Opaque rough may have translucent or transparent sections. |
| Phenomena | Asterism (very rare); color change. |
| Etymology | After J. J. Paris, proprietor of the mine at Muzo, Colombia (1828-1848) where the mineral was first discovered. |
| Occurrence | In carbonaceous shale beds in the emerald deposits of Muzo, Colombia, also as typical inclusions in emerald crystals from Muzo. Also in alkaline granite-syenite pegmatites and hydrothermal deposits. |
| Inclusions | Fractures, fingerprints, two-phase inclusions. |
Parisites, 2.8 x 2.6 x 1.1 cm, Snow Bird Mine, Mineral Co., Montana, USA. © Rob Lavinsky, www.iRocks.com. Used with permission.
Parisite is a group of rare-earth fluorocarbonate minerals. All members of this group are very rare, but the cerium-dominant member, parisite-(Ce) is the most common. The group also includes a neodymium-dominant member, parisite-(Nd) and a lanthanum-dominant member, parisite-(La). Unless otherwise noted, the parisites discussed in this article are of the Ce-dominant variety.
Parisites are most well-known as inclusions within emeralds from Muzo, Colombia. In fact, when found in emeralds, these inclusions are diagnostic of Colombian origins. However, these inclusions occur infrequently.
When parisites occur as larger crystals, they’re still usually quite small and very included themselves. These crystals seldom have areas clean or large enough to facet. Mineral collectors prize these specimens, too, which makes faceted pieces especially hard to come by.
Parisite crystal on calcite, from the G.J. Brush collection at Yale University #2813 (1972). Scale at bottom of image is an inch with a rule at one cm. Muzo Municipality, Boyacá Department, Colombia. Photo by Rock Currier. Licensed under CC By 3.0.
Very rarely, cabbed parisites may display asterism, the “star stone” effect.
In a 2021 study, researchers documented a color change effect in a parisite specimen from Colombia, from reddish brown in daylight to yellowish brown in artificial light.
Freeform step-cut parisite, 0.71 cts, 5.2 x 5 mm, Muzo, Colombia. © The Gem Trader. Used with permission.
With a hardness of just 4.5, parisites can be scratched very easily. Distinct cleavage and fractures also make these stones more likely to break if accidentally struck with force. They also lack brilliance and dispersion and generally occur in earth-tone colors. Most faceted pieces are very small, too.
Generally speaking, parisites don’t have many of the properties that would appeal to most jewelry enthusiasts. On the other hand, these stones may interest collectors of rare minerals and unusual gemstones as well as aficionados of earth tones.
Use protective settings for any parisites worn as jewelry and reserve them for occasional wear.
Parisites also have another notable property which may dissuade many consumers from wearing them. All parisites — Ce, Nd, and La-dominant — are weakly radioactive. However, for the amount of material you’re likely to encounter, the radiation dosage is virtually negligible. You can use this radioactivity chart for parisite-(CE) to estimate your potential exposure.
To put this into perspective, the average annual estimated exposure in the U.S. from background radiation, medical sources, and consumer products is 360 mRem. If you held 100 grams (500 cts) of parisite in hand, it would take nine days to equal your annual estimated exposure. However, that’s an extraordinarily large quantity of a rare mineral. If you held 1 gram (5 cts) in hand, it would take 750 days to equal a year’s worth of average radiation. At 0.1 gram, a half-carat stone, the radiation is negligible.
In the quantities mineral collectors or jewelry enthusiasts are likely to possess, parisites should pose no significant health hazard from radioactivity.
Of course, gem cutters and faceters should take precautions against accidentally inhaling or ingesting particles from any materials they cut. Lapidaries should follow the recommendations for working with radioactive materials in our safety guide. You can find additional safety information on webmineral.com.
There are no known lab-created parisites or gem enhancements.
Colombia is the principal source of most gem-quality parisites, particularly the Muzo Mine.
In the United States, Ravalli County and the Snowbird Mine in Mineral County, Montana have produced crystals that have yielded small, faceted pieces.
Mount Malosa, Malawi produces large, opaque, and heavily included crystals. However, some of these crystals may have gem-quality portions. The yield is small, but the deposit appears to be extensive.
Other notable sources of crystals include the following:
When backlit, these parisite crystals show a rich brown-red color and partly gemmy interior. 1.9 x 1.2 x 0.9 cm. Zagi Mountain, Hameed Abad Kafoor Dheri, Khyber Pakhtunkhwa, North-West Frontier Province, Pakistan. © Rob Lavinsky, www.iRocks.com. Used with permission.
Most parisite crystals are usually small, so as a result, most faceted pieces weigh under one carat. However, larger crystals can occur. Crystals from Muzo have weighed up to 385.66 cts. and prismatic crystals from Mount Malosa have measured up to 20 cm long. Pakistan has also produced crystals over 8 cts. Thus, the potential exists for larger faceted pieces, but inclusions make parisites difficult to cut, especially in large sizes.
The Smithsonian Institution has a 10.794-ct oval-cut cabochon in its collection. The Edward J. Gübelin Collection has a 5.38-ct cushion-cut specimen. Both of these gems were cut from Colombian parisites.
Don’t clean parisites with ultrasonic or heat systems, since inclusions may burst and shatter the stones. Clean them only with water, mild detergent, and a soft brush. Consult our gemstone jewelry cleaning guide for more care recommendations.
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