The Collaborative International Dictionary of English v.0.48:

Manganic \Man`gan"ic\, a. [Cf. F. manganique.] (Chem.)
   Of, pertaining to resembling, or containing, manganese;
   specif., designating compounds in which manganese has a
   higher valence as contrasted with manganous compounds. Cf.
   Manganous.
   [1913 Webster]