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Sec. II, Ch. 2: The African Diamond

Sec. II, Ch. 2: The African Diamond Page of 366 Sec. II, Ch. 2: The African Diamond Text size:minus plus Restore normal size   Mail page  Print this page
86                             African Diamonds.
to Stelzner this rock is a pikrite-porphyry, much altered, and he believes that, though destitute of Diamonds, it was derived from the same subterranean source whence the blue earth took its rise.
The volcanic material rising from below, and bringing with it the Diamonds, ascended the pipes ; but these were not all filled at the same time, nor was the blue earth of one pipe due to a single ascent of the material. Thus both in De Beers' and in Kimberley the " blue " of the west side is unlike that of any other part of the mine ; it carries but few Diamonds and these present distinctive characteristics.
An ingenious hypothesis regarding the origin of the Diamond-bearing pipes and their contents has recently been enunciated by Sir William Crookes, who has lately returned from a visit to South Africa. He suggests that a solution of the perplexing problem as to the genesis of the South African Diamond may be readily found in the assumption that they have been formed from deep-seated masses of metallic iron in a molten condition, under enormous pressure and at a temperature so high as to be comparable to that of our electric furnaces. This molten iron held carbon in solution, and on solidifying under pressure the carbon would crystallize out as Diamond, just as it does in M. Moissan's experiments ; only in nature the pressure might be vastly greater than in our labor­atories and the process of cooling might be continued through ages of time, so that large crystals would be produced by natural means, whereas the crystals formed in our laboratory experiments are mere microscopic specks. If. water, passing downwards, gained access to the heated materials, it would give rise to vast volumes of steam and other gaseous products, which rushing upwards could rend
Sec. II, Ch. 2: The African Diamond Page of 366 Sec. II, Ch. 2: The African Diamond
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