938 THE JOURNAL OF GEOLOGY. 
augite and olivine are more or less completely replaced by 
biotite. 
The division of the series into three parts is for convenience. 
The classes will be described in the order just given under the 
names: Adsarokite, Shoshonite and Banakite. 
ABSAROKITE. 
All of the rocks here classed as absarokites carry abundant 
phenocrysts of olivine and augite, except two that are included 
with them on grounds of chemical identity. They occur in the 
Absaroka range, and in other parts of the Yellowstone Park; at 
the north base of Sepulchre Mountain; upon Mirror Plateau ; 
within the Crandall volcano; at Signal Point, Yellowstone Lake ; 
at Two Ocean Pass, and in Ishawooa Canyon, and elsewhere. 
The chemical composition of five of these rocks is shown by the 
following analysis. Table I.* 
TABLE I. CHEMICAL ANALYSES OF ABSAROKITES, YELLOWSTONE 
NATIONAL PARK AND VICINITY. 
I 2 3 4 5 
S10, - - 47.28 48.95 48.36 51.76 49.71 
TOs - - - .88 -49 1.18 BUT) 15 9/ 
Al,O; - - 11.56 12.98 12.42 12.36 1 3),330) 
Fe,03 - - - 3.52 3.63 5.25 4.88 4.41 
FeO - - 5.71 4.68 2.48 4.60 Bayi 
MnO - - - ot 3} 5113) it si 3h 7/ 
MgO - - 1 Qo 7 TI7? 9.36 9.57 7.96 
CaO - - - 9.20 7.66 8.65 7.14 8.03 
BaO - - apeatihcs Saar .29 pres .46 
Na,O - - 2.89-2.73 2.31 1.46 1.99 1.49 
K,0O - - 222-2107, 3.06 3.97 3.83 4.81 
P50; - - 59 .67 84 56 .66 
Cl - - - .18 teas Sette sued Sek 
H,O - - - 2.96 3.16 5.54 3.05 4.07 
100.08 100.35 99-93 100.32 100.01 
Less O forCl - = .04 
100.04 
tMost of the analyses cited in this paper have already been published in the 
paper by the present writer on the Origin of Igneous Rocks. Phil. Soc. Washington. 
Bull. Vol. XII. pp. 89-214. Washington, 1892. 
