226 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



6. NORTH AMERICA. 



The occurrence of the diamond in the United States of North America is so sparing 

 that it has no effect whatever upon the diamond markets of the world. American stones 

 are, however, greatly prized in the States, both for patriotic reasons and also on account of 

 their scientific interest. 



There are two principal diamond-producing regions, one in the extreme east and the 

 other in the extreme west of the country ; the former occupies the eastern slope of the 

 southern part of the Appalachians, while the latter lies at the western foot of the Sierra 

 Nevada and the Cascade Range. 7?hough the two regions are so widely severed, yet in each 

 the stones occur under very similar conditions, being found in loose detrital materials, in 

 gravel and sand, and everywhere in association with the same minerals, namely, garnet, 

 zircon, magnetite, anatase, monazite, and specially with gold, in the search for which 

 diamonds are frequently found. This agreement in the mode of occurrence of the diamond 

 in the two regions, must be attributed to the fact that in both the detrital material has 

 been derived by the weathering and denudation of the crystalline silicate rocks of which the 

 surrounding mountains are built, and that these rocks are essentially identical in character 

 in both regions, although those of the east are older than those in the west. 



A third diamantiferous district has been recently discovered, namely, the region of the 

 Great Lakes ; here the stones have been found in glacial deposits mainly in the State of 

 Wisconsin, but also in Michigan and Ohio. 



According to Mr. George F. Kunz, the well-known American expert in precious stones, 

 a considerable number of diamonds have hitherto been found in the eastern region, in the 

 States of Georgia and North Carolina, very few in South Carolina, and still fewer in 

 Kentucky and the southern part of Virginia. From Virginia came the " Dewey " diamond, 

 the largest ever met with in the United States. It was found by a labourer in 1855 in an 

 excavation in the village of Manchester, and had the form of an octahedron with rounded 

 edges, weighing in the rough 23f carats and when cut llyi- carats. This stone is not of the 

 purest water and its beauty is impaired by other flaws, so that it would not be actually 

 worth more than 300 to 400 dollars (about £6^ to cfSS) ; in spite of this, however, it has 

 been sold for about ten times this amount. It was the only specimen found at this spot. 



In North Carolina diamonds have been found, usually associated with gold, in the 

 district about the east foot of the Blue Ridge. The mountains of the district are built up 

 of crystalline schists ; itacolumite, the flexible sandstone which occupies so important a 

 position in the Brazilian deposits, is also found here, though at present no diamonds have 

 been discovered in it. The stones hitherto met with are for the most part octahedra ; the 

 largest yet found, weighing 4J carats, was discovered in 1886. A stone valued at 400 

 dollars is said to have been found in South Carolina ; in this State, as in North Carolina, 

 diamonds are found associated with gold and in the vicinity of itacolumite ; the largest, an 

 octahedron of 4ji2^ carats, was found in 1887. About the year 1886 a single small stone was 

 found in a river sand in Kentucky. 



During a search for gold in Wisconsin, at the end of the eighties, a few small diamonds 

 were found associated with grains of quartz, magnetite, ilmenite, and with grains and 

 crystals of the varieties of garnet known as almandine and hessonite (or perhaps spessartite). 

 A few large diamonds have been found in this State; thus in 1893 an almost colourless 

 stone, weighing S^r carats, and having the form of a rhombic dodecahedron, was found in 

 clay at the town of Oregon, Dane County. Previous to this, in 1876, a yellow diamond of 

 the same form and weighing 16 carats was found with several others near Eagle in Waukesha, 



