The Diamantiferous Rock of Kimberley

Abstract

My friend, Dr. Hatch, is not quite correct in stating (January 9, p. 225) that I was led to dissent from the late Prof. Carvill Lewis's view that the diamantiferbus, rock of Kimberley was a volcanic peridotite “by a microscopic examination made in 1899 of specimens from the Newlands Mines” (Proc. Roy. Soc., lxv., 1899, p. 223). Four years earlier I expressed the opinion that this rock was a breccia, and that the diamonds, with other conspicuous minerals, were not formed in situ (Geol. Mag., 1895,. p. 500). This belief was strengthened rather than shaken by editing Prof. Carvill Lewis's notes and examining his specimens (“The Genesis of the Diamond”), and was expressed yet more decidedly later in 1897 after examining another series of specimens from Kimberley (see Geol. Mag., 1897, p. 501). To discuss the “magma” and “concretion” hypothesis would be out of place here, but elsewhere I may have something to say on those subjects.