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Ch. 1: Diamonds

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32
GEMS AND PRECIOUS STONES IN THE
tained a small quantity of strongly aromatic crystalline body, volatile, burning easily with a smoky flame, and melting at about 50°C. Unfortunately the quantity obtained was too small to admit of a full investigation of its composition and properties. He suggested that perhaps the diamond was formed from hydro­carbon simultaneously with this aromatic body. Prof. H. Carvill Lewis, at the meeting of the British Association at Birmingham, in September, 1886, in a paper "On the Genesis of the Dia-mond," stated that from the Do, Beers' Mine, in South Africa, at a depth of 600 feet, there had been sent him specimens of unal­tered rock which proved to be peridotite containing carbonaceous shale. He added that information received from New South Wales, Borneo, and Brazil led him to believe all diamonds to be the result of the intrusion of a peridotite through carbon-/ aceous rocks and coal seams. The similarity of the South African peridotite to that described by Joseph S. Diller in Kentucky led Professor Lewis to suggest interesting possibilities as to the occurrence of diamonds there ; and on the invitation of Prof. John R. Proctor, State Geologist of Kentucky, in the summer of 1887, Mr. Diller and the writer were sent, by Major John W. Powell, t-he Director of the United States Geological Survey, to make an investigation. The locality is easily reached by way of the East Kentucky Railroad, which ends in Carter County, at Willard, where conveyances may be obtained of the farmers for the remaining ten miles. The best exposures of the peridotite occur along Ison's Creek, in Elliott County. The peridotite alters and disintegrates readily, but because the declivity of the surface here is considerable, the transportation of material almost keeps pace with disintegration, and there is no great accumulation of residuary deposits upon the narrow divides and hillsides. The specific gravity and durability of the gems found in connection with peridotite are generally greater than of serpentine and other products of its alteration. On this account they accumulate upon the surface, and in favorable positions along adjacent lines of drainage. The plan followed was to search by sifting and care­fully panning the beds, receiving the drainage directly from the surface of the peridotite, and to enlist the services of the people
» Am. J. Sci. III., Vol. 32, p. 121, Aug., 1886.
Ch. 1: Diamonds Page of 364 Ch. 1: Diamonds
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Kunz. Precious Stones of North America.
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