ABSTRACT
Ca 4 MgB 12 As 2 O 28 ·18H 2 O multinary compound [mineral teruggite (Rodgers et al. 2002; Aristarain and Hurlbut, Jr. 1968; Dal Negro et al. 1973)], which crystallizes in the monoclinic structure with the lattice parameters a = 1,567.5 ± 1.3, b = 1,992.0 ± 1.4, c = 625.5 ± 0.4 pm, and β = 99°20′ ± 5′ and the calculated and experimental densities of 2.192 and 2.20 g cm−3, respectively (Dal Negro et al. 1973) [a = 1,568 ± 1, b = 1,990 ± 1, c = 625 ± 1 pm, and β = 100°05′ ± 10′ and the calculated and experimental densities of 2.139 and 2.149 ± 0.005 g cm−3, respectively (Aristarain and Hurlbut, Jr. 1968)], is formed in the B–H–Ca–Mg–O–As system.
