In-pattern tetrad effect-like variation, so far overlooked, but obviously observed in REE abundances of REE minerals

Rare earth elements in REE-rich minerals were determined accurately by isotope dilution mass spectrometry (IDMS). The chondrite normalized REE patterns of some specimens showed regular relative aberrations, which are similar to that of the 'tetrad effect'. We have introduced a background curve passing normalized values of La, Nd, Gd, Er and Lu, to measure the aberations. The relative differential variations of some of the minerals are not small, but have been overlooked due to large overall variations of the chondrite normalized values.