CsCoF3has hcp (h) and ccp (c) CsF3layers alternatinghhchhchhcat atmospheric pressure (9Lstructure of BaRuO3) but acchcchsequence (6Lstructure of RbNiF3) if quenched from 700°C at pressures greater than 20 kbar. The octahedral‐site Co2+ions are between the layers and give the 9Lstructure a pink color, the 6Lstructure a lavender hue. The 9Lphase obeys a Curie‐Weiss law above 70°K withCm=3.7 emu°K/mole and &THgr;p=−62°K. It hasTN=8°K with evidence for a spin‐flop transition atHc≈11 kOe and an anisotropy constantK≈5×104ergs/cm3at 4.2°K. The 6Lphase hasCm=3.3 emu°K/mole, &THgr;p=−65°K and is ferrimagnetic belowTC=50°K. The magnetization is not saturated at 17.2 kOe and 4.2°K, where &mgr;¯=0.8 &mgr;B/Co2+is smaller than the 1.23 &mgr;B/Co2+anticipated at saturation for RbNiF3‐type ordering. Optical data show a larger trigonal‐field splitting for the 6Lstructure. For both phases,Dq≈760 cm−1, spin‐orbit interaction parameter &zgr;≈500 cm−1, and long wavelength cutoff≈13 &mgr;m.