This compound is a misfit-layered oxide consisting in two monoclinic subsystems with identical a, c, and b parameters, but different b parameters:
a=4.8376(7) Å, c=10.833(1) Å, beta=98.06(1)°, b1=4.5565(6) Å, and b2=2.8189(4) Å. The structure is built up from the stacking along c of triple rock salt-type layers Ca2CoO3 ~first subsystem! with single CdI2-type CoO2 layers ~second subsystem!.
----------------------------------------------------PRB,62,166(2000) http://prb.aps.org/abstract/PRB/v62/i1/p166_1