Filmy Oxyde of Manganese

This, although not very conspicuous, is a curious mineral and is worth distinction, being very little known. It Will now probably be readily recognized by the figure and description, and be preserved in greater plenty and better specimens. The specimen here drawn is a mixture of the usual dull Oxyde of Manganese, with the black Hydro-oxyde of Iron, and I think the metal used with the silvery and tarnished lustre rather happily represents it as lying in a thinish film upon the gangue. It is not unusual near Exeter; my specimen was among Mr. Day’s, which I have now had for some years it frequently lines the hollows in masses of mammillated hydro-oxyde of Iron.