Diamonds
9781465636843
400 pages
Library of Alexandria
Overview
From the earliest times the diamond has fascinated mankind. It has been a perennial puzzle—one of the “riddles of the painful earth.” It is recorded in Sprat’s History of the Royal Society (1667) that among the questions sent by order of the Society to Sir Philiberto Vernatti, Resident in Batavia, was one inquiring “Whether Diamonds grow again after three or four years in the same places where they have been digged out?” The answer sent back was, “Never, or at least as the memory of man can attain to.” In a lecture “On Diamonds,” fifty years ago, Professor Maskelyne said, “The diamond is a substance which transcends all others in certain properties to which it is indebted for its usefulness in the arts and its beauty as an ornament. Thus, on the one hand, it is the hardest substance found in nature or fashioned by art. Its reflecting power and refractive energy, on the other hand, exceed those of all other colourless bodies, while it yields to none in the perfection of its pellucidity.” He was constrained to add, “The formation of the diamond is an unsolved problem.” Diamonds are found in widely separated parts of the globe. In the United States they have been found in Arkansas, where the work of testing the deposits is now going on steadily and quietly. The general geology and petrography of the area and the weathering of the peridotite are described in a paper read before the American Institute of Mining Engineers by Messrs. Kunz and Washington. In tests made with a diamond drill the peridotite was proved to depths of 200 feet. The green and yellow grounds underlying the layer of black, sticky soil are found to extend down 40 feet in places, and are estimated to average 20 feet in depth over the area. The outcrop of the peridotite is estimated to cover about 40 acres, and may be larger. Some 540 diamonds have been found, with an aggregate of 200 carats. The largest stone weighs about 6·5 carats, though the average size compares favourably with the general run of most of the South African mines. There is a large proportion of white stones, many of which are free from flaws and are very brilliant. The genuineness of the occurrence of diamonds in their matrix is again proved, one stone having been found imbedded in the green ground at a depth of 15 feet. This peridotite has the form of a volcanic pipe, and therefore its outcrop is limited to one place. In California authentic finds of diamonds are recorded in Butte County, especially at Cherokee, above Orville. These diamonds, however, have come from alluvial deposits and have been found generally in washing for gold. As yet no authenticated discovery of diamond in its original matrix in California is recorded. In Brazil the diamond industry has been increasing of late years, and the old mines in the Diamantina country are being worked by American capital and by the American methods which have proved so successful at De Beers. It is estimated that the annual value of the diamonds exported from Brazil amounts to over £800,000, but it is impossible to arrive at accurate figures owing to the large quantities smuggled out of the country to avoid payment of the export tax. British Guiana produces a small quantity of diamonds, mostly, however, of small size. Between January and September, 1907, 1564 carats were exported. Indian diamonds chiefly come from the states of Panna, Charkhari, and Ajaigarh. In 1905 India exported 3059 carats, valued at £5160.
