92 



NEW YORK STATE MUSEUM 



that shown in plate 13, lower figure, suggesting very strongly the 

 postgranitic hyperite dikes observed in other parts of the western 

 Adirondacks by Professors Smyth and Gushing (Gushing, 1905, 

 pages 327-30). 



Under the microscope (see plate 17, upper figure), the rock is 

 seen to consist of hornblende, augite and andesine, with a lesser 

 amount of garnet and some accessory apatite, magnetite and ortho- 



/'_'^L"-i xL^'^^.' I'll I L^ r '\|\L\,^^ i"_i I L' l^^ *^,^^ N\ I '',^'', ^i"^ 



-^-IN--I^- l(-\l - -\|^-K-.I-\I-I -l^-X- \ - , - 



X, _>'_|''_V|_-' 





" 1--- 







a 





ff^i^ 



1 ^^— 



Fig. 20 Ground plan of knob of rock shown in plate 16, lower figure, (a) 

 Granite gneiss, considerably sheared; (&) gabbro with indistinct foliation. 

 Knob about 30 feet in longest diameter. 



One and six-tenths miles northeast of Pyrites. 



clase. Most of the hornblende occurs independently of the pyrox- 

 ene, but occasionally an augite crystal incloses secondary shreds and 

 patches of greenish amphibole, or is otherwise associated with the 

 latter in such a manner as to indicate its derivation from the pyrox- 

 ene. The garnet, which occurs in small scattered crystals and not in 

 the laro-e skeletal masses common to the garnet gneisses and to the 



