CLARKE.] 
IGNEOUS AND CRYSTALLINE ROOKS. 
75 
R. Grorudite, about 2 miles north of the summit of Chisos Moun- 
tain. Grorudose-pantellerose. Contains alkali feldspars, and sub- 
ordinate quartz, with riebeckite and regirite in irregular interstitial 
patches. Sp. gr., 2.648, 15.5°. 
S. Pulaskite, Santiago Mountain. NordmarkoHe. Consists of alkali 
feldspars, with subordinate oegirite, aegirite-augite, riebeckite, mag- 
netite, and rare lovenite. Sp. gr., 2.581, 25.5°. 
T. Syenite-porphyry, Iron Mountain, near Marathon. Nordmark- 
ose. Contains many oligoclase-albite phenocrysts in a groundmass of 
alkali feldspar, with very little quartz. Titanite, apatite, and mag- 
netite are present in small amounts. Sp. gr., 2.5T7, 15.5°. 
U. Essexite, Big Hill Canyon, Rio Grande. Essexose. Contains 
predominant orthoclase, soda-rich plagioclase, and nephelite, with 
considerable augite, olivine, and magnetite, and small amounts of biotite 
and apatite. Sp. gr., 2.686, 25.5°. 
R. 
Si0 2 
A1A 
FeA 
FeO 
MgO 
CaO 
Na 2 
K 2 
H 2 Oatl05°.... 
H 2 above 105° 
Ti0 2 
Zr0 2 
C0 2 
PA 
s 
MnO 
BaO 
SrO 
Li 2 
Rare earths 
68.25 
13.60 
3. 66 
1.43 
.02 
.54 
6.52 
4.73 
.16 
.32 
.26 
.25 
trace 
.02 
trace 
.04 
trace 
trace 
trace 
.08 
99.88 
62.46 
17.10 
2.49 
2.65 
.28 
1.27 
6.84 
5.44 
.15 
.49 
.38 
.10 
trace? 
.11 
none 
.18 
none 
none 
trace j 
.03 
T. 
99. 97 
65. 47 
17.93 
2.15 
.43 
.06 
1.10 
6.21 
5.21 
.19 
.41 
.29 
.07 
trace ? 
.19 
trace 
trace 
. 16 
trace 
none 
.05 
r. 
99.92 
53. 34 
17.92 
2.27 
5. 51 
1.40 
4.19 
6. 41 
4.32 
.58 
2.08 
1.60 
trace 
trace ? 
.44 
.03 
.17 
.09 
.06 
trace 
.05 
100. 46 
CI, F, not looked for. 
