Ch. VI. ] QUARTZ LODES. 95 



sulphur, that it reduces the mercury to its metallic 

 form again, and prevents its being carried off in light 

 mineralised flakes and powder. 



The band of auriferous quartz veins worked at Santo 

 Domingo continues westward for eight miles, as far as 

 the savannahs near Libertad, and has been largely 

 mined in the neighbourhood of that town, and between 

 that point and Santo Domingo. Besides the working of 

 the mines proper, some surface deposits, called by the 

 Spaniards " Mantos," are also worked for gold, espe- 

 cially in the neighbourhood of Libertad. The 

 " Mantos ' consist of broken quartz, covering the 

 faces of the hills in the neighbourhood of some of 

 the lodes. In some places they form a broken 

 but regular stratum over the whole side of a hill, 

 and I was much puzzled at first to account for their 

 origin. 



I have already mentioned that the lodes near their 

 summit incline over towards the face of the hill through 

 which they cut. In some cases, as in the San Antonio 

 mine, the lode is in parts bent completely round, as 

 shown in the annexed section. This bending over of 

 the lodes is always towards the face of the hill, and is, 

 I think, produced by successive small land slips. It is 

 evident that if carried still further than in the case 

 shown in the diagram, the lode would be brought down 

 over the face of the hill, and the result has, I think, 

 been achieved in some places, and a regular " Mcuito '' 

 produced. I have already stated that small landslips 

 are of frequent occurrence on the sides of the hills. 

 We had several times the entrance to our mines closed 

 by them in the wet season. 



