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THE ORIGIN AND FORMATION OF THE DIAM 



By W. Johnson, L.R.C.S., L.R.C.P. 



For many years I worked at the problem of the origin of 

 diamonds and of the possibihty of manufacturing them by arti- 

 ficial means, trying more especially to discover and follow the 

 methods pursued by nature in this matter, and I now propose 

 to record some of the results at which I have arrived. 



Before the discovery of the South African Diamond Mines all 

 the diamonds found, first, in India, and afterwards in Brazil, 

 were found in material that was generally allowed to be of secondary 

 origin, and, therefore, of comparatively little value in throwing 

 light on the actual origin of the diamond. The discovery of 

 diamonds in this country, however, considerably lightened the 

 problem, and the investigations which followed served to narrow 

 down the question to a much smaller area. 



Some authorities have held, even with regard to the South 

 African Mines, that the diamonds were derived from an extraneous 

 source and not formed in the mines themselves. The Dwyka 

 conglomerate, for instance, has been named as a possible source. 

 By others the eclogite boulders and concretions have been credited 

 with being the original matrix. In this case, however, we do not 

 need to look outside the mines for the source, as the concretions 

 and boulders containing diamonds may quite well have been 

 formed within the mines themselves, at a certain stage of their 

 existence. 



Leaving the theory of the origin of terrestrial diamonds from 

 meteorites to the idealists who hold that view, there is only 

 one other theory, that the diamonds were not formed in the 

 mines themselves, that we need notice, and that is the theory 

 of Moissan, Sir William Crookes, and others. This theory sup- 

 poses that the diamonds were first formed deep down in the 

 earth in masses of molten iron, by the disintegration of which 

 they passed later on into the blue ground of the mines. This 

 theory derives its plausibility from the fact that small diamonds 

 of microscopical size have been formed by suddenly cooling molten 

 iron that has been saturated with carbon at a high temperature. 

 Many take it that this theory has settled the question of the 

 origin of the diamond in the mines once for all ; and although 

 several objections have been launched against it, the great authority 

 of those who support it, and the positive results of the experiments, 

 however meagre, have so far maintained its prominence. I 

 say, " however meagre," because the largest diamond produced 

 in this way does not exceed 75 of a millimetre in length. Mr. 

 Gardner Williams, late General Manager of De Beers, than whom, 

 as Sir William Crookes once said, no man living knows more 

 about diamonds, has consistently opposed this theory from 

 the first. I will refer to it later on. 



