These rare earth oxides form from the leftover elements that other minerals seem to not want. Other rare earth oxides such as fergusonite and euxenite have very similar properties to samarskite and are often associated with each other, compounding the problem. Even the common oxide, rutile , is almost indistinguishable from these rare earth oxides without chemical tests when rutile is found massive.
Samarskite is found in rare earth rich granite pegmatites, a slow cooling igneous intrusive rock.
Samarskite is associated with quartz , feldspars , columbite , tantalite and other rare earth minerals. Samarskite is common enough and locally abundant enough that it has potential to be a valuable resource for its rare earth metals. But it is its gemstone use that is what is odd about this mineral. As mineral specimens, samarskite can be a nice addition to one's collection. Good crystals are rare, but prized when found.