20 
30 
2s 
20 
Analyses 
of 
Percentage 
30 
Basanite 
Atkaline ™ 
-Gasalts ¢ 
7 INK us 
Silica Percentages of Igneous Rocks. 437 
LAVAS 
Fig. Ia. Fig. Ib 
Basalt 
“I 
A 
‘ 
i) 
wrsmoothed smootied 
. A 
40 so re ee o re 
Limburgite Fi é nt f 
‘ 
a 
+! Dolerite ’ Rhyotite 
ih ‘ 
\Basalis: x a Mai Dacntelo' 
' «Andesite o. ' 
, Ain! 
%o Si02 
so 
Fig. I. 
% S102 
80 90 
Tephrite Fig. IV. 
Phonolite 
a a a A 70 80 BY 
