Adjective : ferriferous rock.    From Dictionary.com. 

Only ferriferous workplaces (steel and cast materials) are permitted to be machined on the magnetic chuck.    From Wordnik.com.  [3. Preparing face and parallel milling] Reference

Rather than a distinct species, it is really a ferriferous variety of enstatite, which owing to partial alteration has acquired a bronze-like sub-metallic lustre on the cleavage surfaces.    From Wordnik.com.  [Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria"] Reference

The ferriferous varieties are liable to a particular kind of alteration, known as "schillerization," which results in the separation of the iron as very fine films of oxide and hydroxides along the cleavage cracks of the mineral.    From Wordnik.com.  [Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria"] Reference

The headland rose more than sixty feet above the sea-level, and the azure waters of the Mediterranean, as they softly kissed the strand, were tinged with the reddish hue of the ferriferous rocks that formed its base.    From Wordnik.com.  [Off on a Comet! a Journey through Planetary Space] Reference