inorganic compounds
Crystals of the -(AlMnSi) (aluminium manganese silicon alloy, Al4Mn1.01Si0.74) cubic 1/1 approximant phase for the icosahedral quasi-crystal were prepared from an Al72Mn16Si12 alloy under an argon atmosphere. The structure is reproduced by the connection of two large atom clusters with icosahedral symmetry (a Mackay icosahedron and double-Mackay icosahedron) [Yang (1988). Phil. Mag. B58, 47-57]. Si and Mn atoms are suggested to constitute icosahedral arrangements in the atom clusters. The crystal structure of -(AlMnSi) was determined previously by Cooper & Robinson [Acta Cryst. (1966), 20, 614-617].