378 



C. A. SUSSMILCH AND W. G. STONE. 









Chemical Composition. 









Per cent. 





Per cent. 



Si0 2 ... 



... 



62-85 



S (FeS 2 ) 



absent 



A1 2 3 





.. 



13-58 



Cr 2 3 



absent 



Fe 2 3 







1-95 



NiO and CoO 



absent 



FeO ... 







5-45 



MnO 



0-14 



MgO ... 







1-92 



BaO 



o-io 



CaO ... 







4-10 



SrO ... f 



present 



Na 2 







3-32 



Li 2 



f absent 



K 2 0- 







0-88 



v 2 o 3 



trace * 



H 3 O(100° 



C 



) 



0-20 



CuO 



trace * 



H 3 O(100° 



co 2 ... 



c 



.+ 



) 2-50 

 1-85 











99-92 



TiOn 







0-90 







-i- i\_f 2 • • • 



Zr0 2 ... 







absent 



Specific gravity 



2-753 



P 2 5 ... 







0-18 



* Trace less than 0-01% 



S0 3 ... 







trace* 



f Spectroscopic reaction only 



CI ... 







trace* 













Norm. 









Per cent. 





Per cent. 



Quartz 





25-56 



Ilmenite 



1-67 



Orthoclase 





5-56 



Apatite 



0-34 



Albite 





27-77 



H0 25 C0 2 etc. 



4-55 



Anorthite 





19-74 









Hypersthene... 



11-80 





99-77 



Magnetite 







2-78 







Class II. Dosalane. Rang 3 Tonalase. 



Order 4. Austrare. Subrang 4 Tonalose. 



Magmatic name Tonalose. 



Arriving at the actual mineral constitution from the 

 norm, it is evident that the average plagioclase felspar is 

 one in which soda predominates over lime, and, therefore, 

 approximates to the andesine group, and plagioclase also 

 largely predominates over orthoclase. 



