I give another extract from this admirable guide book of South Africa, as bearing upon this subject: “In the part of Namaqualand called Bushmanland, and which is a vast table-land about 3,000 feet above the sea, are immense deposits of what Mr. Dunn calls glacial conglomerate. These extend westward into the sovereignty (Free State), and in them in a sort of tufaceous limestone deposit seem to occur the diamond deposits which have made that region so famous.”
Dr. Ure, in his “Dictionary of Arts, Mines and Manufactures,” states: “The ground in which diamonds are found in the mines of Brazil is a solid or friable conglomerate, consisting
Dr. Ure, in his “Dictionary of Arts, Mines and Manufactures,” states: “The ground in which diamonds are found in the mines of Brazil is a solid or friable conglomerate, consisting chiefly of a ferruginous sand, which incloses fragments of various magnitude of yellow and bluish quartz, of schistose jasper, and grains of gold disseminated with ologist iron ore, all mineral matters different from those that constitute the neighboring mountains. This conglomerate, or species of pudding-stone, almost always superficial, occurs sometimes at a considerable height on the mountainous table-land.”
Dana says: “The original rock in which diamonds are found in Brazil appears to be either a kind of laminated granular quartz called itacolumite, or a ferruginous quartzose conglomerate. The itacolumite occurs in the Urals, and diamonds have been found in it, and it is also abundant in Georgia and North Carolina, where diamonds have also been found, while in India the rock is a quartzose conglomerate.”
The following extract which also bears upon the subject is from a report by Mr. C. F. Osborne, M. E. on the Knysna gold fields, and may prove both interesting and valuable, and this I have taken from a blue book of the Cape parliament of May, 1886:
“The mineral character of the rocks is in some respects peculiar, and they differ much in reality and very much in appearance, from the gold-bearing rocks of Australia or California, and even from those of the Transvaal; and the average Australian digger, judging from appearances merely, would doubtless, at first sight and without trial, pronounce them non-auriferous.... There are several reasons why these rocks present such a difference in appearance from those of the gold-bearing countries I have named. One is that the principal gold-bearing rock here is itacolumite, a rock which does not exist, or is very sparingly developed, in Australia, the Transvaal, and in the greater part of California, but which is abundant and characteristic of the gold regions in Russia.”
I will not dilate upon the above extracts as to the source of the diamondiferous soil, and will pass on to the origin of the diamonds themselves. All authorities state that the diamond is intimately connected with gold and platinum, but I cannot find any record which convinces me of the diamond having been found in the matrix—that is to say, in the rock in which it was originally formed—as all the formation in which the diamond has been found appear to have been the detritus of older rocks, in which it by some means or other had become imbedded during the formation of the newer one.
In “Precious Stones and Metals,” by C. W. King, M. A., which is a very learned and exhaustive work, I find the following: “Pliny remarks that the diamond is the companion of gold, and seems only to be produced in gold itself. He is here correct, although perhaps it may be but by an accidental coincidence; for all the diamond mines, the discovery of which is recorded, have been brought to light in pursuit of alluvial gold washings.”[[28]] Mr. King proceeds to remark: “The British Museum, amongst the native diamonds, exhibits an octahedral diamond attached to alluvial gold; and, strange confirmation of the ancient idea as to their affinity, not only is the primary crystal of that metal also the octahedron, but also its secondary modifications exactly correspond with those of the diamond. Modern science has made no further advance toward the solution of this problem beyond that propounded as a certainty in the ancient ‘Timæus.’”