104 DESCRIPTIONS OP MINERALS. 



in Ellore. In Borneo, they are obtained on the west side of 

 the Ratoos Mountain, with gold and platina. The Brazilian 

 mines were first discovered in 1728, in the district of Serra 

 do Frio, to the north of Eio de Janeiro ; the most celebrated 

 are on the river Jequitinhonha, which is called the Diamond 

 River, and the Rio Pardo ; seventy to seventy-five thousand 

 carats are exported annually from these regions. In the 

 Urals of Russia they had not been detected till July, 1829, 

 when Humboldt and Rose were on their journey to Siberia. 

 The river Gunil, in the province of Constantine, in Africa, 

 is reported to have afforded some diamonds. 



In South Africa, where they were first discovered in 1867, 

 they occur in the gravel of the Vaal River, and in the 

 Orange River country. The value of the diamonds obtained 

 up to November, 1875, has been estimated as exceeding 

 60,000,000 of dollars. 



In the United States, the diamond has been met with in 

 Rutherford County, North Carolina; Hall County, Georgia ; 

 also Franklin County, North Carolina ; in Manchester, 

 opposite Richmond, Virginia ; also in Cherokee Ravine, 

 Butte County, Forest Hill in El Dorado County (one weigh- 

 ing nearly 5 -62 grains), Fiddletown in Amador County, and 

 in Nevada County, California; and on the coast of Southern 

 Oregon. It has been reported from Idaho. 



The original rock in Brazil appears to be either a kind of 

 laminated granular quartz, called itacolumyte ; or a ferru- 

 ginous quartzose conglomerate. The itacolumyte occurs in 

 the Urals, and diamonds have been found in it ; and it is 

 also abundant in Georgia and North Carolina. In India, 

 the rock is a quartzose conglomerate. The origin of the 

 diamond has been a subject of speculation, and it is the 

 prevalent opinion that the carbon, like that of coal and 

 mineral oil, is of vegetable or animal origin. Some crystals 

 have been found with black uncrystallized particles or seams 

 within, looking like coal ; and this fact has been supposed 

 to indicate such an origin. 



Diamonds, with few exceptions, are obtained from allu- 

 vial washings. In Brazil, the sands and pebbles of the 

 diamond rivers and brooks (the waters of which are drawn 

 off in the dry season to allow of the work) are collected and 

 washed under a shed, by a stream of water passing through 

 a succession of boxes. A washer stands by each box, and 

 inspectors are stationed at intervals. 



