Abstract
The crystal structure of the synthetic mineral lonecreekite, (NH 4 )Al 0.59 Fe 0.41 (SO 4 ) 2 .12H 2 O (I) has been determined from single-crystal X-ray diffraction.The crystal structure contains Centro symmetrical octahedral [M(H 2 O) 6 ] 3+ (M = Al 3+ and Fe 3+ ) and [(NH 4 ) + (H 2 O) 6 ] cations as well as (SO 4 ) 2-anions.The M 3+ -OH 2 distance is between the analogical distances for Al 3+ and Fe 3+ cations.The M cation and N atom are placed on inversion 3-fold axis (4(a) and 4(b) special positions).The sulfate anion is distributed in two mutually pseudo reversed positions with the relative occupancies 0.91 and 0.09.The S and two mutually opposite posioned O atoms of the disordered sulfate anion are placed on a 3-fold axis (8(c) special position).The H atoms of the (NH 4 ) + group are not located, but the geometry of the eight short contacts of the N atom corresponds to the H-bonds and shows that cation is oriented in two positions related to each other by an inversion center.