ELIZABETHTOWN AND PORT HENRY QUADRANGLES 



45 



never reach the great sizes of the labradorites in the coarse anortho- 

 sites, but range not far from the dimensions of those of the ordi- 

 nary granites. The green feldspar is the chief component but with 

 it are dark silicates sometimes in relatively large amount. Quartz 

 is not lacking entirely but can not often be seen by the unaided 

 eye. The analyses which have been prepared especially in con- 

 nection with Professor Cushing's work show percentages in silica 

 which usually range between 60 and 65 or under those of typical 

 granite but there are close relatives both above and below these 

 values. The potash and soda are generally present in nearly equal 

 amounts. 



The following analyses have been selected to illustrate the rur^ of 

 composition. None are based on samples taken in the area covered 

 by this bulletin, but they represent all sides of the Adirondack 

 region, and undoubtedly could be duplicated in the former. Later 

 analyses of a series from Mineville will be given, which depart in 

 both directions from the compositions here cited. The Ticonderoga 

 case, no. 5, is the nearest to the Elizabethtown and Port Henry 

 quadrangles. The sample was taken near the railway crossing of 

 the Lake George outlet and is about 15 miles from Port Henry. As 

 soon as one examines these analyses, they are seen to be obviously 

 closely akin. The low magnesia and the nearly balanced alkalies 

 are striking. 



ANALYSES OF SYENITES. 



Si02 



•AI2O3 



Fe203 



FeO 



MgO 



CaO 



I 



68.50 



14.69 



1-34 



3-25 



.26 



2-20 



2 



66.72 



16. IS 



1.23 



2.19 



2.30 



3 



64.47 



10.51 



I. II 



5.21 

 3.10 



4 



63-45 



18.38 



1.09 



2.69 



•35 

 3.06 



62.41 



18 -75 



2.49J 



4.91J 



.61 



3-17 



6 

 61.01 

 15-36 



75 



78 

 05 



7 



59 70 



19-52 



1. 16 



5.65 



•78 



336 



1 Quartz-augite syenite. Altamont, Franklin co. Analyzed by E. W 

 Morley for H. P.- Gushing. N. Y. State Mus. Bui. 115. 1907. p. 514. 



2 Augite-syenite. Little Falls, Herkimer co. Idem. 



3 Syenite, gneissoid. Whitehall, N. Y. Analysis by W. F. Hillebrand 



4 Augite-syenite. Loon Lake, Franklin co. Analyzed by E. W. Morley 

 for H. P. Gushing, who considers the occurrence as typical. Geol. Soc, 

 Am. Bui. 10. 1900. p. 177. Revised in N. Y. State Mus. Bui. 115. 1907. 

 p. 514. 



5 Augite-syenite. Ticonderoga, Essex co. Analysis by M. K. Adams. 



6 Augite-syenite. Altamont, Franklin co. Analyzed by E. W. Morley 

 for H. P. Gushing, as under no. i. 



7 Augite-syenite. Line of townships 22 and 23. Franklin co. Analyzed 

 by E. W. Morley for H. P. Gushing, as under no. i. 



