100 ANALYSES OF ROCKS AND MINERALS, 1880-1908. 
The four following rocks, from the Colorado Springs quadrangle, were collected 
by G. I. Finlay. Descriptions furnished by Cross. Analyses by G. Steiger, record 
No. 2236. . 
H. Riebeckite granite, Rosemount. Contains quartz and alkali feldspar, with 
considerable amounts of riebeckite, less barkevikite, and very little zircon, magne- 
tite, and titanite. 
I. Aplitic granite, east of St. Peters Dome. Consists,chiefly of quartz and alkali 
feldspar, with small amounts of riebeckite and a mica rich in iron. 
J. Micaceous granite, east of Fairview. Rich in lepidomelane and riebeckite, with 
quartz and alkali feldspar. Accessory constituentsrare, fluorite probably among them. 
K. Lamprophyre dike in granite, Bear Creek Canyon. Consists of alkali feldspar, 
plagioclase, and hornblende, with small amounts of biotite, quartz, muscovite, and 
other minor accessories. 
H I J K 
ILO 15 2s, sieasiaysigpesesajaies eae eae goign che oe eee 73.82 | 77.31 | 73.22 61. 46 
DUO $i oy syzissds aves ceeta) aie eisaye eoecereyersisteiciseemieeensrse es 10.59 | 12.45] 10.93 14.55 
Bei O avcoeheeaaienatabosd ad nu ate switedowdawe cadens 2.18 - 43 3.94 2. 30 
FeO. 2.98 +33 1.20 5.78 
MgO 04/ none} none 
CaO. 28 -50 41 2.74 
NazO 4,20 4.72 3. 63 4.71 
K20 
QI... --- ES! = 
HeO Gt 105s vc ccinerwis oe oe meeseragesede si giseey onrreeen nore hanes kl 39 ~ 42 87 54 
Elis OVD OVO LOSS op. susp ceciapeicinnsingan se tec acinlaee ans ei cidiaie eins oeasceaaioge alee ISS 49 -40 99 74 
TIO gs 2-06 13 - 06 22 1.07 
ZrOz. none} none| none 02 
P2035. 02) none} none 27 
Bice 06 «15 10 14 
Biz none |} none| none 01 
MIO scsiecciacicctnerem sc nee nenciciviag creme circa ttn ieineeeian aaa Soe ea bias aE none -O1 03 25 
Ba wosaccuesexectahcexneees eet ow aoweeenenesasenie eee seeee Eas eeesee s none |} none} none 7 
99.75 | 100.62 | 100.13 | 100.13 
CSSA O a cnais disconecnieg2 cibibie ecleisieie tig Eee s enepeiuislenSeiaiedioun uae Gace Queciat dedaynunes 0: 0 0. 06 
COz and SOz absent; SrO not looked for. 
ROCKS OF THE CRIPPLE CREEK DISTRICT. 
Rocks A to L described by Cross. Descriptions published, except when other- 
wise stated, in 16th Ann., pt. 2, pp. 38-50. Analyses, with two exceptions, which are 
properly noted, by W. F. Hillebrand, record Nos. 1448, 1453, and 1524. - 
A. Phonolite, dike in granite northeast of Big Bull Mountain. Miaskose. Con- 
tains anorthoclase, nepheline, sodalite, egirine-augite, some exgirine, biotite, magne- 
tite, and limonite. Nosite not distinguishable. P. R. C. 616. 
B. Phonolite, Mitre Peak. Miaskose. Contains sanidine, nepheline, sodalite, 
zegirine, nosite, and colorless particles which may be lavenite. P. R. C. 608. 
C. Phonolite, hill 1 mile south of Straub Mountain. Miaskose. Contains anortho- 
clase, sanidine, nepheline, sodalite, nosite, analcite, and egirine, with sometimes 
egirine-augite. P.R.C. 612. 
D. Phonolite, Rhyolite Mountain. Miaskose. Contains nepheline, nosite, anal- 
cite, egirine, and some egirine-augite, in a feldspathic groundmass. Sp. gr., 2.52, 
23°, P. R. C. 618. 
E. Phonolite, between Florissant and Manitou. Miaskose. 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. Con- 
tains sanidine, nepheline, hornblende, with accessory pyroxene (?), magnetite, 
apatite, and sphene. Sp. gr., 2.576, 13°. P. R. C. 607. 
F. The portion of E soluble in hydrochloric acid. This portion amounted to 25.39 
per cent, and is recalculated here to 100. Analysis by Eakins, 
