GOLD AND SILVER MINING 207 



to the point where the lower outcrop of the vein began, and 

 as it flowed, with the aid of a pick and shovel, the ore and 

 siirroundinji; material were cut away. This process was 

 continued ])a('kward up the hill until the gully became so deep 

 that the debris was unmanageable. The extent of some of 

 these excavations is enormous. One at Sao Joao da Chapada, 

 a few miles south of Diamantina, is 150 feet deep, 1,000 feet 

 wide, and 2,000 feet long. 



The mass of material washed down was concentrated 

 in the rudest conceivable manner. Even the use of the sluice 

 was not understood, and in its place the gravel was given 

 its first wash in a canoa. This is merely a level section of 

 the canal in which the gravel and debris is carried down. 

 The water is allowed to fall into this level space over a lip a 

 few inches high, and a workman stirs with a sort of rake the 

 gravel at that point. Below the canoa there is an inclined 

 plane covered with hides laid with the hair up in order to 

 3atch the gold that does not sink to the bottom. In addition 

 to the loss of gold inevitable with such a system of w^ashing, 

 the miners lal)ored under the disadvantage of being liable 

 to lose their vein by the falling in of the side rock. And 

 not only did they lose the clue, but it is lost forever. Many 

 of these old mines are undoubtedly still rich, but the veins 

 are so covered up by the debris that their outcrops can not 

 be found and traced. An interesting feature of the larger 

 hillside mines are the mondeas, rectangular masonry reser- 

 voirs, 50 to 80 feet square and 10 to 20 feet deep, made to catch 

 and hold material washed downi by the canal until it could 

 be conveniently worked. They were necessary where the 

 amount of w^ater was large. In the few instances where the 

 old miners exploited veins for which no water was available, 

 they simply dug a hole, open to the sky, carrying out the 

 mineral and earth upon the heads of slaves." 



Gold mining in this primitive fashion was possible only 

 with cheap slave labor. ''Not the slightest improvement or 

 advance was made as the years went by,'' says another ob- 

 server. ''The ruins of an abandoned working in Minas Geraes 

 resemble exactly those of the old world — in Spain, for example, 

 which was to Rome and Carthage what California is to us 



