CsFeF3appears to be a Ne´el type ferrimagnet whose magnetization forms cones of revolution having a 25‐deg angle with the hexagonalcaxis. The moment along the cone angle increases in an anomalous manner in fields up to 25 kG. In addition, the anisotropy energy at 4.2°K is extremely large withK1≈−7.8×106ergs/cm3andK2≈2.2×107ergs/cm3. At room temperature the optical absorption coefficient is about 1 cm−1for wavelengths 6000–8000 Å. In a field of 20 kG at 84°K the Faraday rotation is 100 deg/cm for a wavelength of 6000 Å.