NOME VII. BASALTIN, WITH SIDERITE. 45 



racter belongs to felspar, and some kinds of pe- 

 trosilex ; but as this rock has not the fracture of 

 petrosilex, I think I ought to look upon it as 

 the earth of uncrystallised felspar. Fragments 

 of this rock are found very plentifully spread on 

 this road. I had not time to ascend to the rocks 

 from which these fragments are detached, but I 

 do not doubt, but that these rocks are situated 

 like those of pier re dt corne, which I have de- 

 scribed in the preceding paragraph. Since I 

 have become acquainted with this rock, I have 

 found rolled pebbles of it in the environs of Ge- 

 neva j so true is it, that we find in proportion to 

 what we know."* 



NOME VII. BASALTIN, WITH SIDERITE. 

 [RHAZITE, from Rhazes, A. D. 900.] 



This combination is far from uncommon, and 

 may be found in most basaltic countries. It 

 sometimes occurs even in schistose siderite. 



Basaltin, with siderite, from Saxony. 



The same, from the Faroe Isles. 



* 1136. 



