£;2o 



NEW YORK STATE MUSEUM 



show very little difEerence in composition between the two. Horn- 

 blende is more prominent than pyroxene in the red rock while the 

 reverse is true in the green. Only one analysis has been made of 

 the red rocks, but the rock lends itself readily to microscopic 

 analysis and these have been used to supplement the other. As 

 a test of the matter a microscopic analysis of the rock later ana- 

 lyzed was made and calculated. The feldspars are easily dis- 

 tinguished from the quartz, and judging from those in the other 

 sj^enites were assumed to consist of orthoclase and plagioclase in 

 the ratio 3 : 4, and the plagioclase was assumed to be Ab4 Anj. The 

 hornblende was assumed to have the composition of the hornblende 

 from the quartz-monzonite from Mt Hoffman, Cal.": 



Mode of red syenite (granophyro-hornblende monzonose) from the 

 north boundary of Litchfield park (10-B-2) 



Units 

 Units measured Sp. Gr. by weight % weight 



Microperthite 793x2.6 = 2062 ^ 54-65 



Plagioclase 320x2.6 = 832 = 22.02 



Quartz 146 x 2 . 65 = 387 = 10.24 



Hornblende 117x3.3 == 386 = 10.22 



Magnetite 15x5.2 = 78 = 2.07 



Apatite 7x3.2 == 22 = 0.58 



Zircon 2x4.3 = 9 = 0.22 



Total 1400 3776 loo.oo 



Composition calculated from mode 





Qz. 



Orth. 



Alb. 



Anor. 



Horn. 



Mag. 



Apat. 



Zirc. 



Total 



SiOa 



10.24 



21.27 2 J. . T 7 



3-79 

 3.26 



5-05 

 0.75 

 0.51 

 1 . 12 



1-39 

 1.27 

 0.08 

 0.05 







0.07 



64-50 

 16.81 



A1203 



6 .01 



6.79 







FezOa 





1-43 

 .64 







1-94 

 1.76 



1-39 

 3-37 

 4.22 



5-56 

 0.24 

 . 02 



FeO . . . 















MeO. . . 















CaO 









1.78 





0.32 







NaaO . . 







4.14 



K2O 





5 -51 









PjOs 











0. 24 

 0.02 



0. 15 



F 



j 











ZrOz 



1 











0.15 





1 













Total . . 



10.24 



32.79 



35-10 



8.83 



10 . 22 



2 .07 



0.58 



0.22 



100.05 



I U. S. Geol. Sur. Bui. i68, p. 208. 



