IXTKH.MEDIATE C'HAKAl'TER OF APPALAt'HIAN GRANITES 



27 



Of the grouping above in the scheme of quantitative classification, it will 

 be observed that the first three (toscanose) and the last one (liparose) of 

 the Georgia rocks are sodipotassic, with the remaining one (fourth one of" 

 table) transitional between sodipotassic and dosodic (toscanose-lassenose) . 



Summary of Conclusions. 



The leading facts developed in the study of the acid plutonic rocks, 

 called granites, of the central and southern Appalachian region, may be 

 summarized as follows : 



The rocks are closely similar in mineral and chemical composition, and 

 are predominantly mica-bearing, chiefly biotite with usually some musco- 

 vite, rarely muscovite alone. Hornblende-bearing varieties are comparatively 

 infrequent. Their range in quartz is great, from 13.5 per cent, to 43.5 

 per cent, with an average of 29 per cent., but within the limits for this 

 constituent of acid-granular rocks. Total SiO, for the region averages- 

 71.18 per cent. 



The range in CaO is from 0.48 per cent, to 4.89 per cent, with an 

 average of 1.85 per cent.; and in total alkalies from 4.29 per cent, to 10.24 

 per cent, with an average of 7.69 per cent. Total alkalies are greatly in 



