Monazite
| Monazite | |
|---|---|
 Monazite-(Ce) | |
| General | |
| Category | Phosphate minerals |
| Formula | (Ce,La,Th)PO4 |
| Strunz classification | 8.AD.50 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H–M symbol) |
| Space group | P21/n |
| Identification | |
| Color | Orange, purple, reddish brown, brown, pale yellow, pink, blue, green, gray, |
| Crystal habit | Commonly as prismatic or wedge-shaped crystals |
| Twinning | Contact twins common |
| Cleavage | Distinct on [100] poor on [010] |
| Fracture | Conchoidal to uneven |
| Mohs scale hardness | 5.0–5.5 |
| Luster | Resinous, vitreous to adamantine |
| Streak | White |
| Diaphaneity | Translucent to opaque |
| Specific gravity | 4.6–5.7 (4.98–5.43 for monazite-Ce) |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.770–1.793 nβ = 1.778–1.800 nγ = 1.823–1.860 |
| Pleochroism | Weak |
| 2V angle | 10–26° |
| Melting point | 1900–2100 |
| Other characteristics |  Radioactive if uranium and/or thorium-rich, dull brown cathodoluminescence, paramagnetic |
| Magnetism | Paramagnetic, moderately strongly |
| References | |
Monazite is a primarily reddish-brown phosphate mineral that contains rare-earth elements. Due to variability in composition, monazite is considered a group of minerals. The most common species of the group is monazite-(Ce), that is, the cerium-dominant member of the group.