File:The American Museum journal (c1900-(1918)) (17975610829).jpg

Title: The American Museum journal
Identifier: americanmuseumjo18amer (find matches)
Year: c1900-(1918) (c190s)
Authors: American Museum of Natural History
Subjects: Natural history
Publisher: New York : American Museum of Natural History
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: Biodiversity Heritage Library

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III DDES 117-;. I///'// /.v III! in <i I (;ri.\\.\ 501 fact, as I learned later, lii.s ability was so marvelous that instead of making the dia- monds go to the bottom center as he should have done, he often brought them to the top and picked them off for himself. When I first saw him he was at work, stooping astride a pool about three I'cet across and two feet tleep. By a series of calculated motions he attempted to form a centrifugal force which would serve to center the heaviest material in the bottom of the sieve, and as diamonds are the heaviest of the pebbles, they naturally are the first to respond to the movements. Where diamonds are found, there are likely to be also tin, car- lion, and pulsite, mixed with quartz. These minerals are heaviest next to diamonds, and are therefore also sent to the bottom. The sieve filled with gravel was lowered into the water and turned from left to right while kept in a level position. Then it was quickly lowered and raised in the water and shaken from side to side while being turned around. Finally, it was swung around while tilted. After a few minutes of such work, the man scooped up the top gravel and threw it away; then he added new gravel to that left in the sieve, and repeated the operation again and still again for an hour. By this time, there was left in the sieve only black carbon, brown pulsite, and a small center of tin, in which the diamonds, if any, were to be found. The sieve was now turned upside down on a piece of level canvas stretched out on the ground by means of pegs. From the middle of the overturned residue, he picked out a small but perfectly shaped dia- mond of one half carat. That stone I have with me today as a reminder of the first time I ever saw a diamond taken from the soil. Diamonds are easily identified in the raw state by their peculiar sheen and shape, but if there is any doubt about the stones, the matter can be decided by subjecting them to pressure between two knives. Anything ex- cept a diamond can be crushed. In color they vary from white to pink, blue, yellow, green, and black. Their shapes range from spherical to flat, and include some nearly perfect diamond-shaped gems. A few stones which I saw were so perfect, both in shape and color, that it was difficult to believe they had not been cut and polished by ma- chinery. The largest stone on record for this region weighed fourteen carats; it was found by a pork-knocker nanicii London, who, because of his great size and strength and previous lawless acts, was feared by the other bushinen. At that time he was work- ing for another man, and strange to say, contrary lo tlic precish'lit set by his previous life, lie lunicil tlic stone over to his em- ployci-. 1 clKuict'il to meet him afterward in the interior and asked him how it came about that he ilid not keep the stone for himself. With an unlooked-for show of elo(;uence he said, "Give unto Cajsar what is Ca?sar's, and unto God what is God's—any- way he be too beeg a stone for one feller- man to steal." His employer probably never would have seen the stone if it had been a mere five carats, but for once London had been scared into honesty. The one mine that the colony had, the "Le Desire," was located in the alluvial deposits in an old bed of the Mazaruni, about two hundred miles within the forest. The river had changed its course since depositing this sixty-foot pile of diamond-bearing gravel, which with age had conglomerated, and on
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After the gravel has been worked down to a very thin layer made up of a brown stone called pulsite, small particles of tin, pebbles of carbon, and any possible diamonds, the sieve and its con- tents are turned upside down on the sorting table. The biggest diamonds are usually found right on top in the middle of the heap. With the point of a knife, the sorters flip each pulsite, tin, and carbon pebble, one by one, from the mass, leaving tlic diiimonds on tlie mat

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