Ann: 14.3% Niobium & 70.3% HREO-Rare Earth Element NYF Pegmatite, page-68

Thanks @Kash111 - my bad should have checked.
There are two Samarskites --- one has U,Th which can replace the (YbFe) radical - appologies to chemists and geologists, my chemistry is many years old. The other is sans the radioactive elements.

"Samarskite is a radioactive rare earth mineral series which includes samarskite-(Y), with the chemical formula (YFe³⁺Fe²⁺U, Th, Ca)₂(Nb, Ta)₂O₈ and samarskite-, with the chemical formula (YbFe³⁺)₂(Nb, Ta)₂O₈. The formula for samarskite-(Y) is also given as O₄. Wikipedia"

We shall see.

I also discovered today that the NYF pegmatites are found within the granite body, whereas the spod bearing LCT pegmatites are squeezed out of the granite during the final cooling.

GL all.