126 



Mineralogy of chalanches. 



FeMspar and 



gneiss with 



Granite with 

 tourmalines. 

 Secondary 

 limestone. 



Bent strata. 



Summit. 



granitic, micaceous, and amphibolic rocks. These strata 

 dip to the west at an angle of 60*. Their direction is north 

 and south. This carbonate of lime is saccharoid, and emits 

 a fetid smell when struck. Two of the three strata are a 

 tolerably pure white; the third is gray with a rosy tinge, 

 and adheres to the amphibole, that serves it as a wall. A 

 little distance from this we find white feldspar rocks con- 

 taining garnets; a little farther, gneiss with garnets; below, 

 granitic rocks with tourmalines ; and lastly, proceeding 

 down to Allemont, the proper position of the secondary 

 limestone on the primitive rocks, 



Toward the summit of the mountain we see quartzoseand 

 amphibolic rocks in strata that are bent, and turned back 

 on themselves. Somelimes the doublings and redoublings 

 are very numerous in the same mass. 



The summit of the mountain is schistose amphibofe 

 veined with quartz. It is naked, and in part destroyed, 

 having fallen down in irregular blocks of different sizes. 



The centre of the works is 1514 met. [1654 yards] above 

 the confluence of the Romanche and Olle, or 2159 met. 

 [2359 yards] above the level of the sea. 



The ores of Chalanches are disposed in veins, beds, and 

 nodules; but these different modes are not continued on 

 regularly. 



The veins are infinitely varied. Their magnitude, direc- 

 tion, and inclination vary continually, and are subject to 

 numerous accidents. These veins are in general placed one 

 above another; they are sometimes very near together; they 

 cross each other in every direction ; they preserve no regu- 

 larity either in their course or dip ; they frequently proceed 

 in a direction opposite to what they took at first ; lastly, 

 they sometimes unite, and proceed together for a certain 

 space, after which they separate, perhaps to unite again, or 

 to disappear entirely, and with very different circumstances. 

 The richness of the veins is not more constant than their 

 mode of being. Frequently we find veins yielding 20 or 

 25 parts of silver in 100 of ore, which at a few decimetres 

 [the dec. is near 4 inches Eng.] distance present nothing 

 but a sterile gangue. 

 Beds the same. The beds of ore are not so common as the veins ; they do 



not 



Height. 



Ore*. 



Veins very 

 iiiegular. 



