DOMAIN II. SILICEOUS. 



is less dark, pretty shining, translucent, smooth 

 and even a little unctuous to the touch, soft, 

 easily scratched to grey, changing under the 

 blow-pipe into a translucent glass, which be- 

 comes transparent on the rod of sappare and 

 dissolves, but without effervescence. This coat 

 appears to be of the nature of steatite ; but I 

 have not been able to obtain pieces of it suf- 

 ficiently large to measure its degree of fusibility." 



The rocks of the southern parts of this sum- 

 mit he thus describes, 1993 : 



" 1. Granites perfectly similar to those before 

 mentioned, 1987. 



" 2. Syenites or granitels, that is, rocks com- 

 posed of laminae of black hornblende and white 

 felspar, also laminar, but both in such small 

 parts, that we may as well give the name of 

 trap to these rocks, according to the definition 

 I have given in 1945. 



" 3. A primitive petrosilex, or palaiopetre, of 

 a pearl grey, translucent to two thirds of a line, 

 with a scaly fracture in large and small scales, 

 sufficiently hard to yield bright sparks, but hav- 

 ing a grey streak when scratched by a sharp- 

 pointed steel. Under the blow-pipe we may 

 form globules of 0,45; which indicates the 

 fusibility of pig-iron, 126 or 130 of Wedge- 

 wood. It is a grey glass, semi-transparent, 



