340 



University of California. 



[Vol. 2. 



X - R' 



-"■12-5 lv 21 



formulae:- 



which are fairly well represented by the following 



r " y r ' i 

 t.sR",X,R'J" K 12 " 2 



R"-,X 2 R' 2 ) 

 J 



=R" 13 X 12 R' 2 



TREMOLITE. 



At a single point in locality B contact between the schist and 

 serpentine was observed. Between the beds of dark-colored 

 serpentine and schist here found, a thin layer of a light-colored 

 fibrous mineral was noted. Its contact with the serpentine was 

 distinguished by a series of curved and moulded surfaces, clearly 

 indicating the action of heavy pressure at this point. On the 

 other hand, the mineral was associated with actinolite and glauco- 

 phane, and intergrowths of the light-colored mineral and the more 

 coarsely crystalline actinolite were observed. 



The pure mineral occurs in masses of fibrous crystals of pure 

 white to light gray-green color, which show a pronounced schistose 

 structure. It is easily crumbled into fine needle-like crystals, 

 which are too small to be studied without magnification, but are 



TABLE No. V. 



Analyses of Tremolite , Chlorite, and Talc. 





i 



2 



3 



4 



Si 2 



Al 2 O a 



Fe 2 O a 



Fe O 



Mg O 



Ca O 



56.68 

 1.79 

 1.70 



2.23 



19- 35 

 15.80 



27 38 

 26.15 

 .78 

 12.70 

 1S.92 



27.03 

 20.07 

 4.72 

 16.47 

 18.90 



56.02 

 9.02 



I.IO 



5-14 

 24.10 

 .60 



Na 2 O 



I-I5 



■ 72 

 1.22 



K 2 O 







H 2 O at ioo° 



.10 



2.25 



1.51 

 11.44 



.16 



4-34 



H 2 O above ioo° 



11.78 



99.90 



100.03 



100.91 



100.48 



Tremolite from San Pablo, California. 

 Prochlorite from San Pablo, California. 



Prochlorite from Austria, Vuylsteke, Tscherm. Min. Mitth, N. F., Band 



12, S. 34. 

 Talc from San Pablo, California. 



