Raman spectroscopy of the molybdate minerals chillagite (tungsteinian wulfenite‐I4), stolzite, scheelite, wolframite and wulfenite

Raman spectra of chillagite, wulfenite, stolzite, scheelite and wolframite were obtained at 298 and 77 K using a Raman microprobe in combination with a thermal stage. Chillagite is a solid solution of wulfenite and stolzite. The spectra of these molybdate minerals are orientation dependent. The band at 695 cm −1 is interpreted as an antisymmetric bridging mode associated with the tungstate chain. The bands at 790 and 881 cm −1 are associated with the antisymmetric and symmetric A g modes of terminal WO 2 whereas the origin of the 806 cm −1 band remains unclear. The ν 4 ( E g ) band was absent for scheelite. The bands at 353 and 401 cm −1 are assigned as either deformation modes or as r( B g ) and δ( A g ) modes of terminal WO 2 . The band at 462 cm −1 has an equivalent band in the infrared at 455 cm −1 assigned as δ as ( A u ) of the (W 2 O 4 ) n chain. The band at 508 cm −1 is assigned as ν sym ( B g ) of the (W 2 O 4 ) n chain. Copyright © 2002 John Wiley & Sons, Ltd.