Parisite


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parisite

[′par·ə‚sīt]
(mineralogy)
(Ce,La)2Ca(CO3)3F2 A brownish-yellow secondary mineral composed of a carbonate and a fluoride of calcium, cerium, and lanthanum.

Parisite

 

(named after J. Paris, proprietor of the mine in Colombia where the mineral was discovered), a rare-earth fluorocarbonate mineral having the chemical composition Ca(Ce, La)2 •[CO3]3F2. It crystallizes in the trigonal system and occurs in crystal form and in solid, compact deposits and earthy masses. It has a hardness of 4.5 on Mohs’ scale and a density of 4,320–4,360 kg/m3. The mineral is usually brownish red or wax yellow, vitreous to waxy in luster, and translucent to transparent. It contains 30.56 percent Ce2O3, 10.44 percent CaO, 24.58 percent CO2, and 7.07 percent F. Parisite generally occurs in hydrothermal deposits associated with alkali syenites and granites, although it also occurs as an accessory mineral in nepheline syenites and alkali pegmatites. It is associated with calcite, fluorite, bastnaesite, and other minerals.

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Mineralogical work completed by the company indicated that a wide variety of rare-earth element-bearing minerals have been identified, including apatite, iimoriite, kainosite, gadolinite, allanite, bastnaesite, parisite, brannerite, thalenite, xenotime, fergusonite, synchysite (Y), and monazite.
Biotite is often chloritised and in quite chloritised biotite was found newly formed titanite, together with ilmenite and rare REE-fluorocarbonate (parisite).
As a New Yorker columnist writing from Paris on fashion in 1927 (under the pen name Parisite) she expressed the odd idea that an expensive article of clothing ought to last: "Go ahead and buy an original little Chanel around here if you want to.
In these minerals, the Ba and REE cations are ordered, like Ca and REE in parisite, synchysite and rontgenite, whereas Sr,REE carbonates with bastnasite-like structures are unknown.
Yes, but extraordinary, amazing specimens of the very rare niobophyllite have lately shown up from the locality (see the picture in the October installment of my "what's new in the mineral world" on this magazine's website), and at Munich there were newly collected, superlative cabinet specimens of arfvedsonite kicking around, and Christian Rewitzer (see later) had a sharp, complete, pagoda-shaped crystal of parisite measuring 2.5 cm from the locality.
He also had some excellent specimens from Mount Malosa in Malawi: parisite in crystals to 3 or 4 cm, epididymite crystal groups, aegirine and others.
Also here were lovely, lustrous thumbnail-size clusters of pale to medium-pink fluorapatite crystals; a couple of superb brown parisite crystals approaching 2 cm; and wonderful pale blue, gemmy euclase crystals to a remarkable 7 cm, with sharp wedge-terminations and no side-cleavage wounds at all.
Most of the pictures are, as before, the work of Master Photographer Jeff Scovil, but perhaps one secret of their exceptional success is simply that their subjects are, almost always, absolutely top-quality mineral specimens, including not only predictables such as aquamarine, elbaite, quartz, topaz, epidote, etc., but also relative exotica like gem zoisite, pargasite, ilmenite, bastnasite and parisite. Just to flip through the book and look at these pictures is a major aesthetic experience; and if the supernally water-clear aquamarine crystal shown on p.
Parisite is found in medium-brown hexagonal-tabular crystals to 3 cm, and also as epitactic overgrowths on bastnasite crystals.
In recent decades, the Trimouns quarry has become well known as a source of outstanding crystals of several rare earth element-bearing minerals, including familiar species such as allanite, parisite and bastnasite, as well as very rare ones such as hingganite, iimoriite and dissakisite.
On the same matrix from the same locality, in a very few specimens, one espies very sharp, barrel-shaped crystals of parisite to 1 cm, these crystals being a rich orange-brown in lamplight and fluorescent yellow-green in shortwave ultraviolet light.
Andreas Weerth has been to Pakistan recently, and brought back some good crystals of bastnasite, parisite and xenotime-(Y)--some of them gemmy.