Chemical Composition of Arrvphibole. 



41 



give. The analysis of Kelson, modified by the introduction 

 of 0-27 per cent of fluorine, follow :-■ 



SiO, 



TiO„ 



A1„0" 3 



Fe;0 3 



FeO 



MnO 



MoO 



CaO 



K„0 



Na,0 



H„0 



F" 



O-F, 



36 



86 



1 



•04 



12 



10 



7 



•41 



23 



•35 







•77 



1 



•90 



10 



59 



3 



20 



1 



20 



1 



•30 





■27 



99 



99 





11 







Per cents of 



Ratios 





protoxide bases 



•614 

 •013 



- -627 





•119 



•046 



- -165 





•324 " 





45-9 ) 

 •7 [ 53-2 

 6-6 ) 



•005 





•047 





•189 

 •013 



► -709 



26-6 ) 



1-8 J-35-7 

 7-3 ) 



•052 





•072 





10-1 



•007 J 





1'0 



100-0 



99-88 

 X. Hornblende from Monte Somma, Italy. — 

 The material analyzed was taken from a speci- 

 men showing an aggregate of small greenish 

 black crystals, many of them terminated by 

 faces having a brilliant luster, developed as 

 shown in figure 5, the forms being, m (110), 

 considerably striated, r (011), p (101) and some- 

 times z (121). The material used for analysis 

 floated at 3 - 310 and sank at 3*255, the average 

 specific gravity being 3*283. The results of the 

 analysis follow : — 















Per cents of 





1 



II 



Average Ratios 





protoxide cases 



SiO, 



39*41 



39*55 



39-48 



658 



- -662 





Tio; 



•30 





•30 



004 





ALA 



12*71 



13-27 



12-99 



127 



• 1 TO 





Fe 2 3 



7-30 



7*21 



7-25 



045 



- 1 I - 





FeO 



10*73 







10-73 



149 " 





196 ) 



MnO 



1-14 



•85 



100 



014 





1*9 J-59*c 



MoO 



11*76 



11*17 



11-47 



287 





37-8 ) 



CaO 



12*10 



11*95 



12-01 



214 



^•759 



28-2 ) 



K„0 



2 39 



__. 



2-39 



025 



3-3 [ 35 '1 



Na 2 



1*72 



1-68 



1-70 



027 





3-6 ) 



H 2 



•82 



•95 



•76 



042 





5-5 



F 2 



•05 







•05 



001 J 





•1 



Loss at 



110° 





•12 









0=F. 



100*25 

 •02 



100*0 



100*23 



