AN attempt will be made in this small paper to describe briefly one of the largest deposits of iron known in Tasmania, and it may not be too much to say in any part of the known habitable world. Much travelled mining men have, been heard to declare it the biggest thing of its kind they had ever seen, and this when they had only seen part of it. The discovery of this immense formation was made by the late Mr. C. P. SPRENT and party, of which I was one, in 1877, whilst engaged in marking and cutting out an exploration track from Circular Head, to the south side of the Parsons Hood, which forms the South Bluff of the Meredith Range, to join a similar track completed the previous year from Mount Bischoff to Mount Heemskirk, across the valley of the Pieman.