194 Penfield and Howe — Chemical Composition 



The crystal that was measured was probably twinned about 

 the base, the twinning plane being situated somewhat above 

 the center which accounts for i\ being situated under ?\ behind, 

 and r % under r a in front, which is contrary to the usual arrange- 

 ment of these planes in chondrodite. All of the crystals on 

 the specimen had exactly the same color and general appear- 

 ance and, although only one was measured it was assumed that 

 they all belonged to the chondrodite type. This is rendered 

 all the more probable by the observations of Scacchi* who 

 states that, on a given block from Mte. Somma, usually only 

 one type of humite occurs. The powder that was separated 

 bv the heavy solution varied in specific gravity between 3*194: 

 and 3-215. 



The analyses are as follows : 









Warwick, N~. 



Y 





Specific gravity = 3-168-3-235 











I. 



II. 



III. 



IV. 



Average. 



Ratio. 



Si0 2 



33-85 



33-67 



33-82 



33-86 



33-80 



0-563 



MgO 



55-74 



55-87 



55-78 



55-68 



55-70 



1-396 ) 



FeO 



2-59 



2-64 



269 





264 



•037 j 



A1A 



1-79 



1-87 







1-83 





F 



7-32 



7-26 



7-32 





7-30 



•384 ) 



H 2 



1-43 



1-48 







1-46-f 

 102-73 



-9= -162 \ 







Oxygen 



equivalent 



to F = 



= 3-07 





99-66 









Brewster, 



N. 



Y 





Specific gravity 



= 3-2 



34- 



-3 231. 









I. 





II. 





III. 





Average. 



Ratio 



Si0 2 33-66 





33-48 





33-87 





33-67 



•561 



MgO 54'68 





54-92 





54-78 





54-79 



1-370 



FeO- 5-89 





5-96 





5-99 





594 



•082 



F 5-25 





5*38 





5-31 





5-30 



•279 



H„0 



2-60 



2-44 



2-61 



2-55-4-9 = -294 



102-25 

 Oxygen equivalent to F = 2-23 



100-02 



0-563 

 1-433 



0-546 



0-561 

 1-452 



0-593 



* Pogg. Ann., Erg. B., iii, p. 181, 1851. 



