PETROLOGY 321 



III. Teschenite from Praya, Cape Verde Islands. F. Kertscher, analyst. 

 (F. Eigel, Tschermaks Min. und Petrog. Mitteilungen, vol. xi, 1090, p. 98.) 



IV. Analcite-basalt from Fernhill dike, Sydney, New South Wales. H. P. 

 White, analyst. (Records of the Geological Survey, New South Wales, vol. 7, 

 1902, p. 93.) 



V. Analcite-basalt from Big Baldy Mountain, Little Belt Mountains. Mon- 

 tana. W. F. Hillebrand, analyst. (L. V. Pirsson, Twentieth Annual Report of 

 the U. S. Geological Survey. 1900, part iii, p. 548.) 



VI. Monchiquite from Highwood Gap, Highwood Mountains, Montana. H. W. 

 Foote, analyst. (L. V. Pirsson, Bulletin 148, U. S. Geological Survey, 1897, p. 

 153.) 



The classification of this rock in the quantitative system is shown in 

 the following computation of its norm and position: 



Norm Ratios 



Or 17.241 _ Sal 47.09 



f b 3-JH47.09 aa ^Ito"4eS3* sl - 0rsrIII ' t,llfemuie - 



An lZ.oi 



Ne 14. 20 J L u 2Q 



01 7.20^ 



Di 23.24 



Mt 8 58 i 



II 4.26^ 46 - 33 w K 2 + Na 2 87 



Ap 2.69 Ran - c^O = 45 = 1,9== 2 ' moncnK l ua ^- 



Pr 0.36J 



H 2 3.67 K 9 31 



C0 2 3.72 Subrang, : ^7 _ r ) = — = 0.55 = 4, monchiquose. 



100.81 



SymVjol Name 



III. 6. 2. 4. Monchiquose (?). 



CAMPTONITE* (OUROSE ( ?) ) 



Megascopic character. — The rock is dark steel gray to grayish-black 

 and noncrystalline porphyrinic in texture. The ground-mass varies in 

 texture from fine-grained (granitoid) to dense aphanitic. Phenocrysts 

 of black hornblende and augite, the. former more abundant and of larger 

 size, are fairly abundantly distributed through the rock. A conspicuous 

 feature of the rock is the numerous large and small areas of white and 

 pinkish (flesh) colors of more or less rounded outline, which are prob- 



Order, — = ^Tgo = 0.43 = 6, portugare. 



*A camptonite dike, not shown on the map, figure 1. occurs two miles north 80 

 east of Mount Sidney, Augusta County, which apparently represents a gradational type. 

 In texture and kinds of minerals present, the rock does not differ from the normal 

 camptonite described below, hut the essential difference is in the relative abundance of 

 llghl and dark colored minerals (he greater abundance of the former (feldspars) im- 

 partlng a lighter color to the rock. Analcite is present in aboul <he same amount, but 

 the dark mafic minerals, hornblende, augite, and biotite, while occurring In the same 

 manner as in the normal camptonite, are greatly exceeded in quantity by feldspar, both 

 ■is phencrysts and in the ground-mass. 



