IXTHIUIEDIATI? CtrAKAOTER OP ArPALACTIIAl^ GRANITES 



35 



38.4, and 38.9 per cents., of potash respectively, and are granites. Nineteen 

 have a ratio not exceeding 1 :2, 17 of wliich are classified as sodipotassic and 

 are quartz monzonites ; the remaining 8 have a ratio exceeding 1 :3, are 

 dosodic, and are granodiorites, 



QUARTZ DIORITES. 



Sixteen^ quartz diorites from tiie western United States, showing the 

 range and average in silica, lime, and alkalies, and calculated range and 

 average in feldspar composition, in the table below, have been selected for 

 comparison. Their position in the quantitative classification has been com- 

 puted-. They correspond to the subrang names, adamellose (1), harzose 

 (2), tonalose (7), yellowstonose (4), andose (1), and lassenose (1). 

 Thirteen of these are dosodic, and only three, adamellose (1), harzose (2), 

 are sodipotassic. The range in the percentage of quartz is very wide, from 

 2.5 in andose (dosodic) to 27.1 in lassenose (dosodic), with a total average 

 of 15.6. 



Quartz diorites of Western United States.^ 



GRANODIORITES. 



Eleven^ representative granodiorites from the western United States 

 have been selected for comparison, and their position in the quantitative 

 system of classification computed. The range and average in silica, lime, 

 soda, and potash, corresponding to the respective range and average in 

 normative feldspar, are shown in the subjoined table. They correspond to 



•Clarke, F. W. Bull. U. S. Geol. Survey, No. 228, 1904. 

 Washington, H. S. Prof. Paper, U. S. Geol. Survey, No. 14, 1903. 

 'Average of 16 analyses: California (7), Montana (9). 

 'Clarke, F. W. Op. cit., 1904. 



