1897.] on Diamonds. 495 



of the chemist and the diamond of the mine are strangely akin as 

 to origin. It is conclusively proved that the diamond has not been 

 formed in situ in the blue ground. The diamond genesis must have 

 taken place at great depths under enormous pressure. The explosion 

 of large diamonds on coming to the surface shows extreme tension. 

 More diamonds are found in fragments and splinters than in perfect 

 crystals ; and it is noteworthy that although many of these splinters 

 and fragments are derived from the breaking up of a large crystal, 

 yet in no instance have pieces been found which could be fitted 

 together. Does not this fact point to the conclusion that the blue 

 ground is not their true matrix ? Nature does not make fragments 

 of crystals. As the edges of the crystals are still sharp and 

 unabraded, the locus of formation cannot have been very distant 

 from the present sites. There were probably many sites of crystal- 

 lisation differing in place and time, or we should not see such 

 distinctive characters in the gems from different mines, nor indeed 

 in the diamonds from different parts of the same mine. 



How the great diamond pipes originally came into existence is 

 not difficult to understand, in the light of the foregoing facts. They 

 certainly were not burst through in the ordinary manner of volcanic 

 eruption ; the surrounding and enclosing walls show no signs of 

 igneous action, and are not shattered nor broken even when 

 touching the " blue ground." These pipes after they were pierced 

 were filled from below, and the diamonds formed at some previous 

 epoch too remote to imagine were erupted with a mud volcano, 

 together with all kinds of debris eroded from the adjacent rocks. 

 The direction of flow is seen in the upturned edges of some of the 

 strata of shale in the walls, although I was unable at great depths 

 to see any upturning in most parts of the walls of the De Beers 

 mine. 



Let me again refer you to the picture of the section through the 

 Kimberley mine. There are many such pipes in the immediate 

 neighbourhood. It may be that each volcanic pipe is the vent for 

 its own special laboratory — a laboratory buried at vastly greater 

 depths than we have reached or are likely to reach — where the 

 temperature is comparable with that of the electric furnace, where 

 the pressure is fiercer than in our puny laboratories and the melting- 

 point higher, where no oxygen is present, and where masses of 

 carbon-saturated iron have taken centuries, perhaps thousands of 

 years, to cool to the solidifying point. Such being the conditions 

 the wonder is, not that diamonds are found as big as one's fist, but 

 that they are not found as big as one's head. The chemist arduously 

 manufactures infinitesimal diamonds, valueless as ornamental gems ; 

 but Nature, with unlimited temperature, inconceivable pressure and 

 gigantic material, to say nothing of measureless time, produces 

 without stint the dazzling, radiant, beautiful crystals I am enabled 

 to show you to-night. 



The ferric origin of the diamond is corroborated in many ways. 



