Phil. Mag. Ser. 6, Vol. 7, Pl. II. 
eo 
ve 
if 
fos 

Dattenberg Basalt, unheated. 
unheated. 
Rowley Dolerite 
unheated. 
Rowley Blue 
5 
Fie. 
Fie, 15. 
Fre. 11. 



after heating. 
Dattenberg Basalt, 
after heating. 
Rowley Dolerite, 
Rowley Blue, after heating. 

