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Lukechangite-(Ce) (Type Locality)
Na3Ce2(CO3)4F

     Lukechangite-(Ce) was collected in 1995 from a large pegmatite dike in the nepheline syenite intrusion. Horváthite-(Y) was collected in a different section of the same pegmatite.

     Lukechangite-(Ce) occurs in a late-stage pegmatic portion of an alkaline, highly agpaitic rock. This stage of crystallization favors the presence of cations having weak acid strengths such as Na and REE. During crystallization weak Lewis acids are stabilized by weak Lewis bases such as F- and (CO3)2-. Hence there is a concentration of REE fluorocarbonates in this type of occurrence.

PHYSICAL CHARACTERISTICS:

Color is colorless to pale beige.
Luster is vitreous to silky.
Diaphaneity is opaque.
Crystal System is hexagonal, P63/mmc.
Crystal Habits include tabular, short prismatic and barrel-shaped
   crystals to 1mm.
Cleavage {001} is perfect.
Fracture is uneven to conchoidal.
Hardness is ~4.5
Specific Gravity is approximately 4.02 g/cm3
Streak is white.
Associated Minerals include aegirine, albite, analcime, astrophyllite,
   catapleiite, eudialyte, fluorite, microcline, petersenite-(Ce), sÚrandite,
   siderite and sodalite.
Origin: Named in 1997 in honor of Luke L.Y. Chang (b. 1934),
   University of Maryland, for his contributions to the study of carbonate
   group minerals.

CLASSIFICATION:

Dana System
# 16a.1.7.2

Strunz Classification
# V/C.7-175

REFERENCES:
AmMin 82:1255-1260 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
¤¤

AP
--

MX
--

SS
--

MC
--

HF
--

BR
--

SX
--

FR
--

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