Mineral - Monazite-(Ce)
Monazite-(Ce)
Chemical Properties
Mineral Class
Phosphates
Toxicity
radioactive
Formula
Ce(PO₄)
Unit Cell
a=6.79 b=7.02 c=6.47 β=103° Z=4
Physical Properties
Hardness
5 - 5.5
Streak
white
Density
Heavy (3,5-6)
Cleavage
Distinct after {100} and {010}
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
brownredorangeyellow
Birefringence
0.067
Luster
Resinous
Transparency
translucent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
massive, prismatic, tabular
Formation
(1) Primary, magmatic, as an accessory mineral in fractionated, acidic plutonic rocks (granites, pegmatites) and syenites, formed by the enrichment of incompatible light rare earth elements (LREE) and phosphate.
(2) Metamorphic, formed by recrystallization or new formation from precursor phases under amphibolite to granulite facies conditions.
(3) Sedimentary, as a resistant heavy mineral in placer deposits resulting from mechanical weathering and gravitational accumulation.
Paragenesis
Twinning
Contact and penetration twins after{100}
Rarity
Rather rare
Synonyms
Monazite-(Ce)
Composition
Elements
Mass
P₂O₅
27.40
U₃O₈
0.40
SiO₂
0.40
ThO₂
11.60
Al₂O₃
0.02
Ce₂O₃
59.24
Pb₃O₄
0.10
CaO
1.00
Sri Lanka (Palache et al. 1952)
Groups and Members
Monazite-Supergroup
Monazite-Group