ferreous

from The Century Dictionary.

• Of, pertaining to, or of the nature of iron; made of iron.
• In entomology, of a metallic-gray hue, like that of polished iron.

from the GNU version of the Collaborative International Dictionary of English.

• adjective obsolete Partaking of, made of, or pertaining to, iron; like iron.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Containing or resembling iron.