Abstract
A Mg-analogue of rowlandite-(Y) occurs in a granite pegmatite at Komono, Mie Prefecture, Japan. It is non-metamict, and the seven strongest XRD lines [d in A (I)] are; 4.95(33), 3.64(37), 3.54(38), 3.08(100), 2.68(32), 2.63(28) and 2.09(35).