Chemical and electronic spectral studies of ullmannite (Ni4Sb4S4)

The streak grayish black coloured and almost opaque mineral ullmannite belo nging to France received from Musee De Mineralogie, Ecole Natle, Supre Des Mines, Paris. France, has been investigated by atomic absorption spectrosco py (AAS) and optical absorption spectroscopy. The AAS analysis shows that t he mineral contains the transition elements nickel (1.14%), iron (0.29%), c obalt (0.073%), copper (0.013%), and manganese (0.0031%). The bands observe d at 25967, 24993, 21546, 14966, 12252 and 861 8 cm(-1) in the optical abso rption spectrum recorded at room temperature are assigned to different tran sitions of Ni(II) ion. The following crystal field parameters are evaluated : D-q = 860 cm(-1), B = 840 cm(-1), and C = 3350 cm(-1), respectively. Thes e values confirm the octahedral symmetry for Ni(II) in the mineral ullmanni te.