THE GENESIS OF THE DIAMOND 629 



material are quite common, but thus far those found in which the 

 rock is clearly non-fragmental seem to be exclusively of the type 

 of the so-called "eclogite nodules," which are regarded by some as 

 segregations in the kimberlite magma and by others as transported 

 fragments of a pre-existing rock. In either case the experimental 

 crushing, reported by Mr. Gardner Williams, 1 of 20 tons of these 

 nodules from the Kimberley mine without finding a single diamond, 

 tells strongly against any general hypothesis of genesis based on 

 the sporadic occurrence of these nodules. 



In the statements at hand relative to the occurrence of diamonds 

 in the parts of dikes that are not expanded into pipes, the impression 

 is given that the rock is non-fragmental; but the evidence on this 

 point is not as clear as one could wish. As the case stands at present, 

 and until unequivocal evidence to the contrary is presented, there 

 is a reasonable presumption that a positive, perchance a genetic, 

 relation exists between the diamond and the fragmental condition 

 of the rock in which it occurs. This in turn may mean that the 

 origin of the diamond can perhaps be assigned to reactions between 

 the original rock, or rocks, of the filling and other elements whose 

 introduction was made possible by the fragmenting of the mass, 

 and which accompanied, or followed, the explosive action, if, per- 

 chance, they did not constitute the actual agency that produced it. 



According to ideas generally received among geologists, the 

 explosive action, as such, is but the culmination of previous thermal 

 processes in the sudden production of gases, principally water 

 vapor. The thermal processes may be protracted and varied in 

 action and may occur repeatedly and extend into late phases of the 

 eruptive period and to stages subsequent to it. One of the most 

 important effects of the protracted action would be to saturate the 

 fractured mass of rock with gases and with liquids resulting from 

 their condensation. Various observers have expressed the opinion 

 that this saturation under the conditions implied reached the point 

 of establishing a marked degree of mobility in the mass, converting 

 it into a veritable rock brew. Be this as it may, such a saturation, 

 whatever its degree may have been, would establish conditions in 

 which a certain amount of hydration (serpentinization) of the erup- 



1 Trans. Am. Inst. Min. Engineers, 1904. 



