44 ANALYSES OF ROCKS, U. S. GEOLOGICAL SURVEY. [no. 228. 
NEW YORK. 
I. ROCKS OF THE ADIRONDACK REGION. 
Collected by J. F. Kemp, who furnishes the petrographic data. A 
and G are described by -Kemp in 19th Ann., Part III, p. 383. The 
other descriptions are hitherto unpublished. Analyses A and B by 
George Steiger, record No. 1715; C to G by W. F. Hillebrand, record 
No. 1717. 
A. Wall rock of iron mine near Lincoln Pond, Elizabethtown. 
Camptonose. Varies from norite to gabbro. Chief minerals, green 
augite, hypersthene, brown hornblende, plagioclase, and magnetite. 
Microperthitic feldspar less common. Garnet varies from absence to 
abundance. 
B. Coarse gabbro, top of Whiteface Mountain. Hessose. A pyrox- 
enic phase of the anorthosite. Contains much labradorite, abundant 
light-green augite, brown hornblende, shreds of more or less bleached 
brown biotite, and magnetite. 
Si0 2 
A1 2 3 
Fe 2 3 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 at 100° . . . 
H 2 above 100° 
Ti0 2 
PA 
MO, CoO 
MnO 
BaO 
co 2 
s 
44.77 
12.46 
4.63 
12.99 
5.34 
10. 20 
2.47 
.95 
.12 
.48 
5.26 
.28 
trace? 
.17 
trace? 
.37 
«.26 
100. 75 
53.18 
23.25 
1.53 
1.82 
2.60 
11.18 
3.97 
.86 
.15 
.98 
.45 
.09 
(?) 
.11 
trace? 
.34 
trace 
100. 51 
a Mainly present as pyrrhotite. 
