Close agreement between measured density and density calculated from cell dimensions assuming t h e above formula (see below) substantiates this composition. Gmelin ( I ) lists two basic uranyl chromates, 2U02Cr04.UO,. 81320 and U02Cr04.UOS. 6Hz0, neither of which appears t o correspond t o t h e present phase, although physical data are lacking. CRYSTAL MORPHOLOGY System and Class. \lonoclinic, prismatic. Habit, { 100) prominent, n-ith { 217 i and {201}. Cleavage. ( loo} prominent. X-RAYDIFFRACTION DATA Diffraction Symbol. 2 / ~ n P 2 ~ / indicatc, ing uniquely space group P21/c ( C i h ) . Cell Dimensions. a. = 16.637, bo = 8.385, co =010.490 A., all i
