1** 



MiNKRAtOG^ OP CH.UA^CHEl 



Anthracite. 



High ridge. 



Chalanches an 

 iniartstym ob- 

 ject of study. 



Sketch of its 

 minerals. 



Hatty's 1st 

 class. 



Carbonate of 

 lime. 



Sulphate of 

 lime. 



Sulphatfi of 

 fcarytes. 



The western valley, called the CIos du Chevalier, exhi- 

 bits an interesting object of study, a stratum of anthracite 

 between strata of clay schist with vegetable impressions de- 

 posited on a granitoid breccia. The latter immediately 

 covers the primitive rocks cf gneiss or amphibole, that con- 

 tain the veins of silver. 



Lastly, on the north of Chalanches is a sfh'nrp ridge, that 

 joins the loftiest peaks of the great chain of Belledonne,- 

 which extends from Vizille to Allevard as you ascend to- 

 ward the high mountains of Maurienne. This chain is dis- 

 tinguished for the number and variety of its rich metallic 

 veins. 



The geology of the mountain of Chalanches offers us 

 grand facts, and various subjects of observation with respect 

 to the catastrophes, that have destroyed and overturned its 

 primitive organization ; the violence it hat subsequently un- 

 dergone; the number of its veins, their formation, and con* 

 tinual changes; and the assemblage of so many various 

 substances, separate or combined together, and modified in 

 numberless ways. Of these substances I shall proceed to 

 give a brief methodical sketch, arranged according to the 

 four graud divisions of the system of Haiiy. 



In the first class, acidiferons earthy substances, we have" 

 carbonate and sulphate oi lime. The carbonate is fre- 

 quently found crystallized, and exhibits numerous varieties 

 of form and colour. It is still more various in its combina- 

 tions. Some of its compounds with iron and manganese 

 have been wrought as sparry iron ore. It is mixed with 

 magnesia in large irregular crystals disseminated through 

 steatitic, asbestous, chloritic, and magnesian gangues. 



The sulphate has often been found in transparent crys- 

 tals, sometimes coloured by copper, and lying on a silky 

 amianthus, partly white, and partly rosecoloured from a 

 mixture of pulverulent arseniate of cobalt. These are un- 

 common, and varied in a pleasing manner. 



At "the foot of the mountain, toward Allemont, is a vein 

 of sulphate of barytes, which was formerly explored in 

 6carch of sulphuret of lead, that appeared there to the day. 

 It has some varieties of form and colour, being radiated, 

 granular, compact, and white. 



Of 



