CRYSTAL STRUCTURE OF GOTZENITE *

° Gotzenite is a silicate of Ti, Ca, and Na; its unit cell parameters are: a = 9.667 A, b = 5.731 A, c = 7.334 A, O! = 90°, f3 = 101.05°, l' = 101.31°, space group Pl. The x-ray structure analysis has been carried out on a twinned crystal. The crystal structure of gotzenite is similar to that of rosenbuschite and seidozerite. The relations among these silicates are discussed and the structural interpretation of twinning is given.