furruginous

Alternative form of ferruginous (“containing iron”).

1804 Antoine François comte de Fourcroy: A general system of chemical knowledge The quartzose iron is somewhat difficult of treatment, nevertheless it does not resist the long-continued action of acids any more than furruginous sands and the different species of ochres.

1804 Anthony Florian Madinger Willich: The Domestic Encyclopaedia; Or, A Dictionary of Facts The natural coral seems to receive its colour from iron, as spirit of vitriol acquires from it a furruginous taste; and on calcination, some particles are discoverable among the ashes, that are attracted by the magnet.

Alternative form of ferruginous (“rust-coloured”).

1823 William Scoresby: Journal of a Voyage to the Northern Whale-fishery The caterpillar feeds on the Kola; it is grey, with alternate rows of white and furruginous spines; the pupa yellowish, variegated with black.