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UNIVERSITY OF YIUGINIA PUBLICATIONS 



I. Pinkish granite-gneiss at Cliarlotteburg, p. 68. 



II. Gray granite-gneiss, Kiee's quarries, German Valley, p. 77. 



III. Gray granite-gneiss, 2 miles north of Waterloo, p. 73. 



IV. Gray granite-gneiss, Allen quarry, Waterloo, p. 72. 



V. White granite-gneiss, quarry one mile south of Cranberry Lake, p. 74. 



VI. Gray granite-gneiss, Di Laura's quarry, near Haskell, p. 67. 



VII. Pink granite (pegmatite), quarry at Pompton Junction, p. 65. 



VIII. Dark gray gneiss, Malley's quarry near Morris Plains, p. 70. 



IX. Gray gneiss, Kiee's quarry German Valley, p. 76. 



With only two exceptions (I and VII) NajO moleciilarly exceeds KjO ; 

 in II, III, IV, and VI, Na^O approximately equals KjO; and in V, 

 VIII, and IX, NajO is greatly in excess of KjO. Assigning potash to 

 orthoclase, and the soda and lime to albite and anorthite, respectively, the 

 analyses show the following composition of the feldspars: 



0. Table of feldspar composition of New Jersey granites. 

 (Numbers correspond to table N.) 



The plagioelase molecules as calculated range from a calcareous oligo- 

 elase (AbjAui) to acid oligoclase-albite (AbsAni) with an average of basic 

 oligoclase-albite (Ab^Anj). The orthoclase-plagioclase ratio and the ortho- 

 clase molecules of I, II, III, IV, and VI, correspond to quartz monzonite. 

 In IX plagioelase is more than double potassic feldspar, but the acid char- 

 acter of the former and the amount of the latter are more characteristic of 

 quartz monzonites and granites than of quartz diorites. V and VIII show 

 a large excess of plagioelase over potassic feldspar, and both are below 

 (VIII markedly below) the minimum amount of potassic feldspar for 

 quartz monzonites. VIII differs from V very markedly in excessively low 

 orthoclase, very basic plagioelase, and a very large excess of plagioelase over 

 orthoclase, properties more characteristic of quartz diorites than of quartz 

 monzonites and granites. VII is especially noteworthy for its high ortho- 

 clase, being double that of plagioelase, and the acid character of the latter. 



