THE GENESIS OF THE DIAMOND 455 
of extraordinary pressure and heat, and thus nothing of serious 
importance stands in the way of a thoughtful consideration of the 
hypothesis here presented that the diamond is a secondary mineral 
crystallized out of some carbon-bearing solution that was capable 
of dissolving the rock (or some parts of it) in which it occurs and 
thus of opening space for it. This hypothesis can be easily recon- 
ciled with the geological conditions in which the diamond occurs 
in its parent-rock, in so far at least as these conditions are known at 
present. These, as set forth in my previous paper, combined with 
the present one, are as follows: 
1. The diamond occurs in the form of isolated complete crystals 
closely enclosed in a rock of eruptive origin occurring in dykes and 
pipes and having the readily alterable minerals olivine and pyroxene 
as its leading essential constituents. 
2. This rock, wherever diamonds have been found in it, shows 
evidence of having been fractured after its consolidation to such an 
extent as to permit a sufficiently free circulation of subterranean 
solutions to produce a very advanced stage of alteration in all 
its olivine-bearing portions, so that the only portions that remained 
perfectly fresh are certain unfractured pyroxene-garnet segregations 
free from olivine. 
3. The circulating solutions introduced water (locked up in the 
serpentine and other secondary minerals) and carbon (locked up in 
the calcite) both of which were lacking in the original rock. 
4. The circulating solutions attacked the garnet of the enclosed 
pyroxene-garnet segregations wherever these were sufficiently 
fractured to permit it, producing an alteration crust of secondary 
minerals. Unfractured segregations would naturally be attacked 
only on their surfaces adjacent to the more fractured and thus more 
permeable olivine-bearing portions of the rock, and thus their 
(presumably) rounded original form would be accentuated through 
corrosion, giving them the aspect of water-worn pebbles. 
5. After (or concurrently with) the alteration of the garnet, 
carbon crystallized in the form of diamond adjacent to the secondary 
crust formed on the former mineral, and also, as Beck demonstrated 
in his study of the diamond-bearing nodule from the Newlands 
mine, in the form of graphite. 
