ABSAROKITE-SHOSHONITE-BANAKITE SERIES. 949 
The rock of analysis 4 is closely related to the last. It 
forms a dike near the head of Stinkingwater River. It carries 
more phenocrysts of serpentinized olivine, and is coarser grained, 
though still microcrystalline. The feldspars are more altered 
and less distinct. The mineral composition is like the last rock 
described, but a few of the auyites are bright green, indicating 
an approach to aegerite-augite. 
The rock of analysis 5 is a leucite-bearing variety of bana- 
kite, already mentioned as forming a massive surficial lava flow 
immediately overlying the shoshonite whose chemical composi- 
tion is given by analysis 2 of Table IJ., and which occurs on 
the southeast fork of Beaverdam Creek. Its chemical composi- 
tion is but slightly different from that of the rock last described 
(analysis 4). The rock is dark gray with a somewhat waxy 
luster. It carries small phenocrysts of feldspar, serpentinized 
olivine and a few of augite. It is holocrystalline with a ground- 
mass of microscopic leucites and unstriated feldspars which 
appear to be orthoclase, but may be plagioclase with low angle 
of extinction. There are also microscopic augites and magne- 
tite, and some serpentine, besides a few. patches of light brown 
mica. The phenocrysts are labradorite, serpentinized olivine 
and fewer augites, magnetites and stout apatites. The crystals 
of leucite have the characteristic form and inclusions, and in 
places are somewhat altered. This rock grades into denser, 
finer grained forms, and also into vesicular forms, which have 
the same mineral composition as the more crystalline part of the 
mass. Mineralogically the rock is more suggestive of shoshonite 
than of banakite, owing to the paucity of biotite and more numer- 
ous olivines. But the amount of ferromagnesian minerals is 
smaller than in shoshonite, and the proportion of alkaline-feld- 
spathic minerals greater, which corresponds to the chemical 
composition. 
The rocks of analyses 6 and 7 belong to this series both 
mineralogically and chemically, but are somewhat more siliceous, 
having 5 to 9g per cent. more silica. They might properly be 
given specific names, but at present we prefer to class them with 
