The crystal structure of katayamalite has been determined by Patterson method and refined by the least-squares method using single crystal diffractometer data, giving R = 0.057 for 5785 reflections. Formula: (K,Na)Li.Ca,(Ti,Fe'+,Mn)2[Si60'8].(OH,F)2' Cell dimensions: a 9.721(2), b 16.923(3), c 19.942(3)A, a 91.43(10t, iJ 104.15(11t, 'Y 89.94(10t, space group Cl, Z = 4; or a 9.763(2), b 9.721(2)...