Parisite-(Ce)

Parisite is a rare mineral consisting of cerium, lanthanum and calcium fluoro-carbonate, Ca(Ce,La)2(CO3)3F2. Parisite is mostly parisite-(Ce), however when neodymium is present in the structure the mineral becomes parisite-(Nd).It is found only as crystals, which belong to the trigonal or monoclinic pseudo-hexagonal system and usually have the form of acute double pyramids terminated by the basal planes; the faces of the hexagonal pyramids are striated horizontally, and parallel to the basal plane there is a perfect cleavag. The crystals are hair-brown in color and are translucent. The hardness is 4.5 and the specific gravity is 4.36. Light which has traversed a crystal of parisite exhibits a characteristic absorption spectrum.
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General Information:
 Chemical Formula:
Ca(Ce,La)2(CO3)3F2
 Composition:
(Molecular Weight = 537.24 gm)
Calcium 7.46 % Ca
Lanthanum 23.27 % La
Cerium 28.69 % Ce
Carbon 6.71 % C 
Oxygen 26.80 % O 
Fluorine 7.07 % F 
 Empirical Formula:
CaCe1.1La0.9(CO3)3F2
 Environment:
In calcite veins in hydrothermal deposits.
 IMA Status:
Approved IMA 1987
 Locality:
Emerald mines, Muso, columbia.
 Name Origin:
Named for J. J. Paris, mine proprietor at Muzo, north of Bogota, Columbia.
Physical Properties:
 Cleavage:
[0001] Distinct
 Color:
brown, brownish yellow, grayish yellow, or yellow.
 Density:
4.36
 Diaphaniety:
Transparent to translucent
 Habits:
Acicular - Occurs as needle-like crystals., Striated - Parallel lines on crystal surface or cleavage face., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
 Hardness:
4.5 - Between Fluorite and Apatite
 Luminescence:
Non-fluorescent.
 Luster:
Vitreous - Greasy
 Streak:
white
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