  Anomalous polarization characteristics of magnetic resonance in CuGeO3 doped
with 2% of Co impurity are reported. For the Faraday geometry this mode is
damped for the microwave field Bw aligned along a certain crystallographic
direction showing that the character of magnetic oscillation differs from the
standard spin precession. The observed resonance coexists with the ESR on Cu2+
chains and argued not to be caused by "impurity" EPR, as previously claimed,
but to correspond to a previously unknown collective mode of magnetic
oscillations in S=1/2 AF quantum spin chain.
