Relatively unaltered feldspars from the Gloserheia pegmatite yield an Rb-Sr isochron age of 1062 ± 11 Ma(M.S.W.D. = 90, Sr1 = 0.7023 ± 0.0002) and a Pb-Pb isochron age of 1085 ±28 Ma. The best age of pegmatite crystallization is given by a U-Pb concordia-discordia intersection at 1060+8-6Ma from euxenite
samples. The radiometric ages limit the last major metamorphism in the area to > 1060 Ma, although mild later hydration has reset Rb-Sr mineral dates on muscovite and biotite to as low as ˜850 Ma. O, Sr and Pb isotope data indicate that the pegmatite magma was derived from a mantle source.