JOS DOMAIN I. SIDEROUS. 



curious account of the manner of working those 

 of France, near Angers, may be found in the 

 Journal des Mines. 



In his account of the primitive schisti, Patrin 

 has the following article*: 



Slate of Ural. " Ferruginous schistus. This slate is mostly 

 composed of hardened clay, abundantly mingled 

 with an oxyd of iron, either black or brown, 

 sometimes red or yellow; a little quartz; and 

 much mica. This rock is one of the most com- 

 mon in the northern countries, where iron is 

 singularly abundant. The eastern part of the 

 Uralian chain of mountains, for an extent of 

 about 500 leagues from north to south, is almost 

 entirely composed of this rock." 



The same able author gives the following ac- 

 count of the slate-mines at Charleville on the 

 Meuse, which he regards as primitive; and 

 afterwards of those of Angers, considered by 

 him as secondary. 



" The slate-mines of Charleville are not ex- 

 plored by open quarries, like those of secondary 

 slate, but by subterranean galleries, because the 

 roof of the bed of slate is composed of banks 

 of quartzose schistus, very hard and very thick ; 

 and besides, the slate plunges very rapidly under 



i, 120. 



