Ch. V.] PRIMARY SCHISTOSE ROCKS. 83 



time ; and cannot, after what has been said in the former 

 chapters, escape notice on a careful perusal. 



In Sweden, also, the granitic masses are said to bear the 

 same relations to the primary slates as in Norway. Most 

 German geologists consider that the granite of Saxony is also 

 similarly circumstanced ; and Bonnard and others, contrary to 

 the published opinions of Haussmann, likewise regard the 

 granite of the Hartz, not as the most ancient and fundamental 

 rock of the district, but of a more modern origin, since it is, 

 in many places, regularly interstratified with mica-slate and 

 other crystalline schists, all of which are surrounded by grey- 

 wacke, and appear to repose on the strata of this secondary 

 rock. 



In Saxony, however, the appearances of this kind are of a 

 more doubtful nature. As already observed in a preceding 

 chapter, the granite of the Erzgebirge occurs in insulated 

 masses surrounded by primary slates, as in Cornwall ; and the 

 latter rocks will be found, in the following details, to present 

 other points of similarity. 



Gneiss and mica-slate are the prevailing crystalline schists 

 in this mountainous chain ; the former being the most abun- 

 dant at the eastern, the latter at the western extremity. 



The gneiss varies exceedingly in the proportion of its con- 

 stituent parts, and in the manner in which these are united. 

 At Freyberg it is very micaceous ana schistose, being well 

 adapted for economical purposes ,* whilst at Himmelsfurst, on 

 the contrary, it is of a more granular texture : so that Werner's 

 division of this rock into two kinds may be generally received. 

 The granular variety is often coarsely crystalline, and exhi- 

 bits frequent passages into granite : and near the town of 

 Schwarzenberg, it contains large pieces of whitish and reddish 

 felspar, having a tendency to a prismatic form, which imparts 

 to the gneiss a porphyritic aspect. In the schistose variety, 

 the component minerals are arranged in regular alternating 

 bands. 



This rock contains several subordinate beds, differing from 



G 2 



