36 0. A. Derby — Occurrence of the Diamond la Brazil. 



of Diamantina at distances of from 6 to 15 miles from the city 

 and three or four miles from each other along the course of the 

 river. The upper one, the Canteiro, is situated a mile or two 

 below the bridge on the road to the provincial capital. The 

 Santo Antonio mine is a little above and the Acaba-Mundo a 

 little V'l. )\v the confluence of the Jequetinhonha with its equally 

 famous tributary, Ribeirao do Inferno. The Jequetinhonha is 

 here a wild mountain torrent flowing in an exceedingly rugged 

 and picturesque narrow gorge. The river had been turned for 

 ahort distances by means of temporary dams and wooden sluices 

 and the sand and gravel had been removed from those parts of 

 the bed thus exposed which were known or supposed to be 

 un worked. 



The rocky river-bed was found to be excavated in a most 

 remarkable manner to a depth of 75 to 100 feet below the nor- 

 mal bed, presenting what may be called subterranean eaftoofl 

 filled with fallen rocks, sand and gravel up to the natural level 

 of the rocky and sandy bed. These canons had served as 

 natural launders in which at some time rich diamondd>eariii;i 

 gravel had been deposited. Some of them had been more or less 

 thoroughly cleaned out by former workings and of course refilled 

 tely when the river took possession of its bed. This 

 newly deposited gravel is net considered worth washing, although 

 it contains some diamonds, and in fact since diamond-washing 

 commenced in the river the newly formed deposits consist of 

 material that has already been more or less thoroughly washed. 



Each of these submerged canons presents some peculuu 

 features dependent on the character of the beds and the relation 

 of the river to them. A diagramatic section of each is given 



1^ _#! itu_ 



ne the river runs N. 25° B. along the 

 s of the lower quartzite, dipping 60° to 

 non, several hundred metres long, is 

 oles which are generally confluent below 

 ?rm a nearly continuous underground 

 i pot-holes widen out to three or four 

 they are much narrower. Some are 



