CLARKE.] 
IGNEOUS AND CRYSTALLINE KiXKS. 
141 
The following rocks from the Denver Basin were analyzed by L. G. 
Eakins in the Denver laboratory, but the analyses do not appear in the 
monograph. The subjoined data have been supplied by Whitman 
Cross. 
A. Enstatite-diabase-porphyry, Mount Morrison. Contains labra- 
dorite and enstatite in a groundmass of considerable amount, which 
is colorless and cryptocrystalline, probably feldspathic, and carries 
magnetite and other indistinct ferritic matter. P. R. C. 533. 
B. Augite-andesite, Table Mountain. Contains plagioclase (ande- 
sine), with rare augite and biotite, in a groundmass of plagioclase, 
augite, magnetite, and minor accessories. This rock contained ptilolite 
in its vesicular equivalent. Described in Proc. Colorado Sci. Soc, 
1886, p. 72. 
C. Augite-andesite, a pebble from the Denver beds, Table Mountain. 
A few augite and andesite phenocrysts in a groundmass of oligoclase, 
orthoclase, and quartz (?) grains, with some augite and magnetite. 
Si0 2 .. 
A1 2 3 - 
Fe 2 3 
FeO.. 
MgO. 
CaO.. 
Na 2 0. 
K 2 0.. 
H 2 0.. 
P 2 5 . 
MnO. 
Sp. gr 
99.96 
2. 876, 27° 
56.74 
59.26 
59.29 
18.80 
23.63 
21.27 
.15 
.30 
3.33 
6.91 
.57 
1.04 
5.57 
.31 
1.12 
7.34 
5.93 
5.25 
2.32 
4.94 
3.39 
.77 
4.78 
3.00 
1.09 
.74 
1.63 
.20 
.23 
.07 
.21 
100. 46 
2. 625, 31° 
99.76 
2. 596, 14°. 5 
2. PIKES PEAK DISTRICT. 
FIRST GROUP. GRANITE. 
Described by E. B. Mathews. Analyses by W. F. Hillebrand, 
record No. 1470. 
A. Granitite, Sentinel Point, western part of Pikes Peak massif. 
Contains microcline, microcline-perthite, quartz, biotite, a little oligo- 
clase, and accessory fluorite, apatite, zircon, sphene, magnetite, and 
allanite. P. R. C. 600. 
B. Granitite, near road between Florissant and the Platte River. 
Consists chiefly of microcline in perthitic intergrowth with albite, 
quartz, and biotite. P. R. C. 606. 
