DOMAIN 1. SIDEROUS. 



slate, in large redoubled layers, so as to form 

 masses three or four inches in thickness, enchased 

 in dull white quartz. 



J 822. Beautiful rocks of granular felspar, 

 with long irregular crystals of siderite, which 

 sometimes assume the form of sheaves or di- 

 verging rays. The base of granular felspar has 

 been mistaken for a sandstone. 



2144. Sheaves of black hornblende, two or 

 three inches in diameter, forming a most beautiful 

 effect on a white gneiss. 



164. Siderite, in the form of a sheaf, or rather 

 fan, on granular quartz, or rather felspar. 



1954. Siderite mixed with calcareous parti- 

 cles, ramifying alternately with quartz. 



STRUCTURE III. WALLERITE. 

 Wallerite. 



This rock, as already mentioned, is one of the 

 primitive gruns terns of Werner, but is here re- 

 stricted to a mixture of crystalline siderite with 

 felspar ; the other primitive grunsteins being class- 

 ed after the basalts, to which they more strictly 

 belong. 



Wallerite from Sweden, of black crystalline 

 siderite mixed with felspar. 



The same, greenish black, from Snowdon in 

 Wales. 



The same, from Mount Sinai. 



