ABSAROKITE-SHOSHONITE-BANAKITE SERIES. 945 
The rock of analysis 1 is asurficial lava on Lamar River, south 
of Bison Peak. It is dark gray, with a waxy luster, and has 
abundant phenocrysts of labradorite, augite and olivine; also 
some small amygdules of zeolite and calcite. In thin section it 
is holocrystalline, the groundmass consisting of lath-shaped 
lime-soda-feldspar and considerable orthoclase in zones sur- 
rounding the plagioclase microlites, and also in twinned prisms. 
There are besides augite, magnetite and a little serpentine. The 
phenocrysts of labradorite are twinned with very narrow 
lamellae. Those of augite and olivine are like the phenocrysts 
of these minerals in absarokite. 
The rock of analysis 2 forms a massive lava sheet on the 
southeast fork of Beaverdam Creek. It is dark purplish gray, 
with numerous phenocrysts of labradorite, augite and ser- 
pentinized olivine. A lighter colored variety carries porphyrit- 
ical biotite and amygdules of zeolite. In thin section it is holo- 
crystalline, and resembles the rock just described very closely, 
except that the olivine is serpentinized. The groundmass is 
similar to that of the former, and there is considerable ortho- 
clase. In the variety with biotite there are cloudy patches of 
an isotropic mineral, which may be analcite. The lava sheet 
immediately overlying this one is similar to it in general appear- 
ance, but contains leucite, and is somewhat more alkaline 
(analysis 5, Table III), and will be described in connection with 
banakite. 
The rock of analysis 3 is a surficial lava flow occurrring on 
the top of the table mountain east of Pyramid Peak. In general 
appearance it resembles the shoshonite from Lamar River south 
of Bison Peak (analysis 1), but the phenocrysts are fewer and 
smaller. The rock is holocrystalline and very fine-grained, with 
an abundance of microlites of augite and magnetite. The 
microscopic feldspars are lath-shaped crystals and allotriomorphic 
grains with low double-refraction. There are spots where minute 
grains of augite and magnetite are clustered together and are 
inclosed in a yellowish substance which is almost isotropic, and 
has the outline of leucite. These impure leucites are scattered 
