THE GENESIS OF THE DIAMOND 453 
or at least brought to Europe. They consist essentially of diopside 
and garnet, the former mineral predominating in the sterile nodules 
and the latter in the diamond-bearing one. The small flake 
studied by Beck had the volume of a cube of 7-8 centimeters length 
of side and showed five diamonds on the fractured faces. Six more 
were obtained by crushing some small detached fragments, from 
which it was estimated that the whole flake contained some dozens 
of diamond crystals, and the original nodule from which it was 
broken (said to have been of about the size of a child’s head) some 
hundreds. The diamonds were embedded in the diopside’ or 
between this mineral and the garnet. The granules of garnet were 
covered with a thin dark crust similar in appearance to the well- 
known kelyphite rim found on this mineral in many other rocks 
but apparently of a somewhat different character. This crust was 
not reported on the garnet of the much more abundant sterile 
nodules, and if it occurs at all in them, it is apparently localized in 
certain spots that were not critically examined. 
The accompanying figure reproduced from Bonney shows the 
relation of a diamond crystal to a neighboring granule of garnet 
covered with its characteristic crust, 
which is said to extend also into 
cracks in the garnet. 
Ii, instead of to the diamond, this 
figure referred to any one of the above- . 
mentioned replacement minerals, the Garnet and diamond (diagram- 
following interpretation of the phe- matic, nearly twice natural size): 
: bs (1) Diamond, (2) garnet, (3) kely- 
nomena registered in it would prob- Satie 
ably be accepted by most, if not by 
all, mineralogists who have occupied themselves with the study 
of the genesis of minerals. . 
A dyke, or pipe, of kimberlite containing nodules (segregations) 
of diopside and garnet was subjected to pneumatolitic action that 
introduced water and carbonic acid into the rock, producing the 
serpentinization of a considerable part of it accompanied by the 
formation of calcite. Some of the included nodules (the more 
brittle ones containing more garnet than diopside would have been 
t See figures in Zeit. f. prak. Geol., May, 1808, p. 164. 
