GOLD MINES IN FRANCE. 27g 



tion the earths and oxides are combined with the acids, as ia 

 observed by Motis. liertholitt, in proportions depending 

 .upon a power produced by the respective proportions and 

 the respective affinities of all the ingredients toward- each 

 other. v 



10, IVigmore Street, March, 8, 180$. 



VIII. 



On the Gold Mines in the Department of the here. By 

 Hericart de Thury, Mine Engineer. 



(Concluded from p. 2377 



1 



T is difficult to meet with a vein so regular and well de- Descriptioa ®f 

 fined as that of Gardette. In fact it shows itself both on tnevem - 

 the surface and within the earth for a uniform length of 450 

 met. ; and throughout the whole of this extent it retains 

 exactly the same direction of SSE andNNW, without 

 being broken off or turned aside by any failure or vein ap- 

 pearing at the surface. 



The inclination to the depth of 78 met. [85 yds] to which 

 the last shaft is driven, is pretty regular thoughout its whole 

 height, being an angle of 80°. It has experienced only two 

 slight variations j the first, near the surface, is a slight break 

 of 15 or 20, or at most 25 cent. [6, 8, or 10 inches] with the 

 same direction and inclination as the vein. The second has 

 been found at G-2 met. [68 yds.] deep ; and is occasioned by 

 a small vein composed of lead, copper, and sulphuret of 

 zinc, which has turned the principal vein toward the W N W 

 about 3 met. [near 10 feet] in that part of the vein which 

 serves as its roof. Below this the slope has become more 

 rapid, though its direction remains the same. 



In all the workings the vein of la Gardette has been found Gangue, 

 to consist of compact quartz, which is crystallized wherever 

 the silex did not fill up the whole cavity. This quartz af- 

 fords very various groupes, which are very limpid when di- 

 vested of the oxide of iron that covers them. The quartz 

 constitutes the bulk of the vein, but various different metals 



lie 



