MODE II. BASALT. 3J 



laceous iron ore, and many other substances, be- 

 come prismatic by torrefaction ; and the prisms of 

 starch formed in drying, have often been consi- 

 dered as illustrative of basaltic formations*.'' 



Among the numerous examples of columnar 

 basaltin, it is well known that they often oc- 

 cur of a coarser grain, and mixed with felspar 

 and siderite, thus strictly belonging to the basalt 

 of the ancients. The columns in the north of 

 Italy, supposed to be volcanic, seem chiefly to 

 consist of this substance. I do not however find 

 that the German mineralogists mention their grun- 

 stein, as occurring in a columnar form, though 

 Daubuisson has evinced that grunstein and basalt 

 are the same substance. The analysis of Dr. 

 Kennedy is as follows : 



BASALT. GRUNSTEIN. 



Silex 46 46 



Argil . .... 16 19 



Lime 9 8 



Oxydofiron ... 16 17 

 Water and volatile matter 5 4 



Soda 4 3% 



Muriatic acid ... 1 1 



Loss ...... 3 1| 



100 100 



* Watt, Ph. Tr. 1804. 



