74 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
MONTANA. 
1. MADISON AND GALLATIN VALLEYS. 
Rocks collected by A. C. Peale and G. P. Merrill. Described by Merrill in Proc. 
U.S. Nat. Mus., vol. 17, p. 637. See also Bull. 110, p. 47. 
A. Basalt (?), east side of Bozeman Creek, 24 miles southeast of Bozeman. Ken- 
tallenose. Contains olivine and augite, chloritized and serpentinized. The colorless 
groundmass contains apparently two feldspars and a pyroxene, with grains of iron 
oxide. Analysis by T. M. Chatard, record No. 517. Sp. gr., 2.86. P.R.C. 971. 
B. Pyroxene from A. Analysis by L. G. Eakins, record No. 1046. 
C. Portion of A soluble in hydrochloric acid. Contains olivine, iron oxides, and 
decomposition products. Analysis by Eakins, record No. 817. 
Ka 
H20 at 120°... 
1.04 
H20 above 120 4.38 li i ae 
TO gs. 2 0sc ot eee eee 
PS Oss gare sisteenied gi veiodin oe thogrlnardicle dial soaks ReaigO ais magg ae siyestseuley MoM Me mEeET eS arnt Ade Nerarsiare parce) Bintereiesrere 
OO 3 aseantrcmcawaqowssnereckvneees ce omendeedecwas ereremesdureeeee ver otmeneesexes -33 LOT leccresee 
Oey seenaisawesknveie ciecreten meas kG esebes 6 se emep ay Sebes wisi ee hres tates -10| trace trace 
D. Highly altered porphyrite (?), hills 1 mile north of East Gallatin River, near 
camp No. 6. Rock contains hornblende paramorphs after augite in a devitrified 
pase, with amygdules of calcite, chloritic and ferruginous matter derived from por- 
phyritic augite and olivine. The base is also filled with needles, which may be 
mica. Analysis by Eakins, record No. 820. P. R. C. 968. 
E. Lamprophyre, Cottonwood Creek. Monzonose. Contains porphyritic augite 
and olivine in an indeterminate groundmass carrying augite, iron oxides, and mica. 
Analysis by Chatard, record No. 516. P. R. C. 979. 
