The Collaborative International Dictionary of English v.0.48:

Eruginous \E*ru"gi*nous\, a. [Cf. F. ['e]rugineux. See
   [ae]ruginous.]
   Partaking of the substance or nature of copper, or of the
   rust of copper; resembling the rust of copper or verdigris;
   [ae]ruginous.
   [1913 Webster]