Classification of Rocks. — Spnrr. 
233 
group given is the belugyte group, which is characterized by 
feldspars intermediate between those of the dioritic family and 
those of the diabasic family, and also contains mica, amphibole, 
or pyroxene. The best excuses for the creation of this group 
will be found in the descriptions in the more elaborate 
report.* For the structural type of the belug}'te group 
characterized by porphyritic structure with aphanitic or fine- 
grained groundmass the word aleutyte is proposed. So far as 
yet studied the aleutytes comprise many of the late Tertiary 
and Quaternary lavas along the belt of the Aleutian islands and 
peninsula, hence the name. 
Analyses of rocks of the belugyte group. 
The following analyses of rocks of the belugyte group have been 
made by Dr. H. N. Stokes, of the United States Geological Survey : 
SiO.. 
TiO, 
CO, 
^,0, 
S 
CI 
AUG., 
Fe=03 
FeO 
MnO 
BaO 
SrO 
CaO 
MgO 
K2O 
Na.O 
Li,0 
HgO at no" 
H-0 above no" 
No. 1 
50.23 
1.30 
.25 
.41 
.02 
19.46 
4.21 
4.20 
.07 
.04 
Trace 
10.39 
3-59 
1 .32 
3.08 
Trace 
.16 
1 .01 
9Q-74 
No. 2 
56.03 
1.24 
•13 
Trace 
18.31 
3-47 
4.42 
. n 
Trace 
Trace 
7-43 
3-64 
1. 18 
3.60 
Trace 
.12 
•31 
99.99 
Analysis No. i is of coarse-grained augite-biotite-hornblende be- 
lugyte, which contains .=triated feldspars, abundant pale-green augitc. 
some biotite and hornblende, and considerable pyrite. The feldspars 
*Alaskan vdlume, Twentieth Annual Reiiort, U. S. Gcol. Survey. 
