Washington — Charnockite Series of Igneous Rocks. 325 



An analysis gave the results shown in A of Table I, there 

 being given also the two analyses published by Holland. 



Table I. 



Analyses of Hypersthene Granites. 



A B C D E F 



Si0 2 -. 11-41 15-54 75-30 73*4? 71-85 71*80 



Al 3 6 3 11-00 13-75 11-40 15-42 15'25 14*90 



Fe'() 3 1-04 4-99 5-40 0'26 1"04 1-10 



Feb!. 2-02 n. d. n. d. 0-67 2-56 1-08 



MgO. -. 0-43 0-69 0-60 0'20 0'63 0*39 



CaO 1-02 0-94 0-75 1-35 2'46 2*20 



Na 2 -.. 2-86 1-55 1-45 5'57 3-18 4-17 



K a 6 4-14 3-34 6-13 3"64 3'04 4'11 



H\,0 + 0-20 0-28 n.d. 0-17 0-60 



H„0 - 0-05 



Ti"O a 0-26 trace 0*12 0-58 0*26 



PO none trace 



MnO none .... trace 



way 



E. 



land 



100-59 101-08 101-03 100'79 100*76 100-61 



A. Charnockite (1.3*. "2.3). St. Thomas' Mount, Madras. 

 (9-658). H. S. Washington analyst. 



B. Charnockite. Same locality. T. L. Walker analyst. T. H. 

 Holland, Mem. Ind. Geol. Surv., xxxviii, p. 142, 1900. 



C. Charnockite. Same locality. P. C. Roy analyst. T. H. 

 Holland, op. cit., p. 142. 



D. Hypersthene granite (1.3.2.4). Birkrem, Soggendal, Nor- 

 C. F. Kolderup, Berg. Mus. Aarb., 1896, No. v, p. 98. 



Hypersthene adamellite (1.3.2.3). Jones Sound, Ellesmere- 

 P. Schei analyst. C. Bugge, Rep. 2nd Fram Exp., No. 

 22, p. 18, 1910. 



F. Hypersthene granite (1.4.2.3). Mount Gbon, Ivory Coast. 

 Pisani analyst. A. Lacroix, C. R., cl, p. 21, 1910. 



The material represented by my analysis is distinctly more 

 silicic than that of the other two,* and it is probable that the 

 central mass of charnockite is not entirely uniform, though the 

 variation is apparently not very great. The marked difference 

 in the figures for potash in B and C renders them (one or 

 both), somewhat open to suspicion. The high summations of 

 these two are, presumably, to be attributed to the estimation 

 of FeO as Fe 2 3 . Not a trace of manganese could be detected 

 in A, although this element is almost universally present in 

 igneous rocks. The other analyses will be referred to sub- 

 sequently. 



* Holland mentions dikes cutting the charnockite, which are composed 

 wholly of quartz and feldspar, with no pyroxene. 



