Monazite-(La) is a relatively rare representative of the monazite group, with lanthanum being the dominant rare earth element in its structure.
As such, it is the lanthanum analogue of monazite-(Ce), monazite-(Nd), and monazite-(Sm).
It is also the phosphorus analogue of gasparite-(La).
[4] 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.