Loveringite, (Ca, REE)(Ti, Fe, Cr)21O38 (a member of the crichtonite group) occurs in orthocumulates (plagioclase-bearing orthopyroxenites) of the Last-Yavr intrusion, which obviously represents a fragment of the Proterozoic Fedorova Tundra-Pana & Tundra layered intrusion. The occurrence is situated immediately adjacent to the Archaean wall rocks at a lower structural level of the intrusion. The loveringite is closely associated with a typical intercumulus assemblage (phlogopite, quartz, albite-rich plagioclase, ilmenite, rutile and Ca-amphibole). Its composition is characterized by a relatively low con tent of REE and high concentrations of Cr and Mg. The rellectance values are in good agreement with published data; VHN 100 = 912-1085. The unit-cell dimensions are a= 10.40 (3), c= 20.83 (6) Å.
A. Yu. Barkov, Ye. E. Savchenko, Yu. P. Men'shikov and L. P. Barkova, Geological Institute, Kola Science Centre, Russian Academy of Sciences, 14 Fersman Street, 184200 Apatity, Russia.
Present address: Department of Geosciences and Astronomy, University of Oulu, FTN-90570 Oulu, Finland.