CLARKE.] 
IGNEOUS AND CRYSTALLINE ROCKS. 
143 
SECOND GROUP. ROCKS OF THE CRIPPLE CREEK DISTRICT. 
Described by Cross. Descriptions published, except when other- 
wise stated, in 16th Ann., Part II, pp. 38-50. Analyses, with two 
exceptions, which are properly noted, by W. F. Hillebrand, record 
Nos. 1448, 1153, and 1524. 
A. Phonolite, dike in granite northeast of Big Bull Mountain. Con- 
tains anorthoclase, nepheline, sodalite, aegirine-augite, some segirine, 
biotite, magnetite, and limonite. Nosite not distinguishable. P. R. C. 
616. 
B. Phonolite, Mitre Peak. Contains sanidine, nepheline, sodalite, 
aegirine, nosite, and colorless particles which may be lavenite. P. R. C. 
608. 
C. Phonolite, hill 1 mile south of Straub Mountain. Contains 
anorthoclase, sanidine, nepheline, sodalite, nosite, analcite, and aagirine, 
with sometimes aegirine-augite. P. R. C. 6l2. 
D. Phonolite, Rhyolite Mountain. Contains nepheline, nosite, anal- 
cite, asgirine, and some aegirine-augite, in a feldspathic groundmass. 
Sp. gr. 2.52, 23°. P. R. C. 618. 
E. Phonolite, between Florissant and Manitou. Analysis by L. G. 
Eakins, made in the Denver laboratory, inserted here for comparison 
with the Cripple Creek samples. Described by Cross in Proc. Colorado 
Sci. Soc, vol. 2, p. 167. Contains sanidine, nepheline, hornblende 
with accessory pyroxene (?), magnetite, apatite, and sphene. Sp. gr. 
2.576, 13°. P. R. C. 637. 
F. The portion of E soluble in hydrochloric acid. This portion 
amounted to 25.39 per cent, and is reduced here to 100. Analysis by 
Eakins. 
A. 
B. 
c. 
D. 
E. 
F. 
Si0 2 
59.00 
20.07 
1.58 
.65 
.10 
1.05 
8.34 
5.63 
.24 
2.03 
.29 
.05 
.20 
.12 
none 
trace 
trace 
.07 
.24 
.26 
58.98 
20.54 
1.65 
.48 
.11 
.67 
9.95 
5.31 
.19 
.97 
.24 
.04 
.20 
.26 
none 
none 
trace 
.20 
.28 
58.78 
20.03 
1.87 
.49 
.16 
.83 
9.36 
5.50 
.31 
1.57 
.29 
.03 
.17 
.15 
none 
none 
trace 
.12 
.58 
58.64 
19.62 
2.17 
.42 
.37 
1.24 
8.39 
5.26 
.34 
2.40 
.20 
.03 
.09 
.20 
trace 
trace 
trace 
trace? 
.14 
.23 
60.02 
20.98 
2.21 
.51 
trace 
1.18 
8.83 
5.72 
} ■» 
44.66 
31.59 - 
.95 
A1 2 3 
Fe 2 3 
FeO 
MgO .. 
CaO 
2.25 
18.42 
2.13 
Na 2 
K 2 
H 2 Oatl00°... 
H 2 above 100° 
Ti0 2 
P 2 5 
trace 
Zr0 2 
MnO . . 
trace 
SrO . . . 
BaO... 
Li 2 . 
SO, 
3 
CI.... 
trace 
C0 2 
"ToaTsT 
100. 00 
99.92 
100. 07 
100. 24 
99.74 
