| Monazite-(Sm) | |
| Category: | Phosphate mineral |
| Formula: | SmPO4 |
| Imasymbol: | Mnz-Sm[1] |
| System: | Monoclinic |
| Class: | Prismatic: 2/m |
| Symmetry: | P21/m |
| Unit Cell: | a = 6.725, b = 6.936, c = 6.448 Å; β = 104.02° |
| References: | [2] |
Monazite-(Sm) is an exceedingly rare representative of the monazite group, with samarium being the dominant rare earth element in its structure. It is the samarium analogue of monazite-(Ce), monazite-(La), and monazite-(Nd). It is only the second known mineral with samarium being the mineral-forming element, after florencite-(Sm).[3] The group contains simple rare earth phosphate minerals with the general formula of ATO4, where A = Ce, La, Nd, or Sm (or, rarely, Bi), and B = P or, rarely, As. The A site may also bear Ca and Th.[4]