134: 



^OLIAlsr EOCKS 



Chemical Composition of Volcanic Dust 



OONSTITUENTS 



Ignition (H2O) 



Oxide of iron and alaminium (FesOg and AI2O3) 



Silica (SiOg) 



Lime (CaO) 



Magnesia (MgO) • 



Soda (NasO) 



Potash (K2O) 



7.60% 



7.62% 



16,22 



18.24 



68.92 



65.56 



1.62 



2.58 



Trace 



0.72 



1.66 



2.08 



4.00 



3.94 



99.92 % 



II 



100.74% 



