Micro‐Raman spectroscopy of natural members along CuSbS 2 – CuSbSe 2 join

Micro‐Raman spectroscopy was used to investigate the natural orthorhombic members (space group Pnma ) along the CuSbS 2 –CuSbSe 2 join: chalcostibite Cu 1.01 Sb 1.00 S 1.99 from Dúbrava (Slovak Republic); Se‐rich chalcostibite Cu 1.00 (Sb 0.99 As 0.02 ) Σ1.01 (S 1.29 Se 0.70 ) Σ1.99 and the new mineral příbramite Cu 0.99 (Sb 1.03 As 0.01 ) Σ1.04 (Se 1.82 S 0.15 ) Σ1.97 both from the Příbram uranium and base‐metal district (Czech Republic). Stretching and bending vibrations of the pyramidal SbS 3 groups occur between 350 and 200 cm −1 ; vibrations of SbSe 3 groups are shifted to the range 240–80 cm −1 due to the almost twice heavier mass of Se compared with S. The shift of the ν 1 symmetric Sb‐(S,Se) vibration was observed, yielding 113 cm −1 , and for the ν 3 antisymmetric stretching Sb‐(S,Se), vibration was about 127 cm −1 . The wavenumber of the ν 1 symmetric Sb–S stretching vibrations decreases with increasing Se content—from 336 (in chalcostibite) over 330 (in Se‐rich chalcostibite) to 326 cm −1 (in příbramite), and a similar situation was observed for the case of ν 1 symmetric Sb–Se stretching vibrations from 220 in Se‐rich chalcostibite to 215 cm −1 in příbramite. The trend for the ν 3 antisymmetric Sb‐(S,Se) stretching vibrations is the opposite, from 306 cm −1 in chalcostibite to 314 cm −1 in Se‐rich chalcostibite (Sb–S bonds) and from 180 cm −1 in Se‐rich chalcostibite to 185 cm −1 in příbramite (Sb–Se bonds). These small shifts are probably connected with the influencing of the bonding environment of SbS 3 and SbSe 3 pyramids. The vibrations of Cu‐S(Se) bonds are represented only by less intense bands, and the observed intense bands below 80 cm −1 should correspond to external modes.