IN my paper on the Lizard this rock is mentioned, but without a specific name, for I had not then seen the figure given in 1898 by Rosenbusch (Elemente der Gesteinslehre, 1898, p.51). He calls it Beerbachite, and describes it on p. 219 as one of his Ganggesteine, among those von malchitischem Habitus, quoting an analysis. The name appears to have been given by Chelius to a rock from Frankenstein in the northern Odenwald, where it forms small veins in a gabbro, and has the following analysis: SiO2 = 47·21, Al2O3 = 20·52, Fe2O3 = 7·48, FeO = 5·32, MgO = 4·16, CaO = 8·63, Na2O = 5·17, K2O = 0·33, H2 = 0·34, P2O5 = 0·46, with 0·19 FeS2 and 0·10 hygroscopic water. He states that the rock is fine-grained to compact, not lustrous, grey to pale grey in colour, consisting of a panidiomorphic mixture of labradorite and diallage, with a variable amount of hypersthene and magnetite, and that olivine-bearing varieties occur. In these commonly a brown hornblende replaces the diallage, in which the above-named constituents are pæcilitic. He states that beerbachite also occurs in gabbro near Harzburg and in the Isle of Mull.