Rather more than twelve months ago Sir D. Jephson Norreys, Bart., of Mallow Castle, county Cork, directed my attention to a beautiful mineral which had been obtained by a friend and neighbour of his, Miss Cotter, of Rockforest. Through his kindness I was enabled to see the circumstances under which the mineral occurred ; and also to obtain from Rockforest some fine specimens thereof.

The mineral itself is specially characterised by the peculiarity of its lustre, which it possesses in a high degree, producing an aspect of a very unique character. Concerning the kind of lustre, this is somewhat difficult to define.