GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 231 
The irregularly oval grains of quartz composing from one 
seventh to one quarter of the rock-mass are either clear and 
vitreous, as in the granites from Seven Lakes, or small and 
stained with iron, as in the rocks collected in Caylor Gulch. 
They are somewhat poor in fluid inclusions but show a great 
number of fine ‘‘quartz-needles.’”’ The iron-staining occurs as a 
filling in the cracks, rather than as a minutely disseminated pig- 
ment or fine evenly distributed hematite flakes. 
Like the granites of the Pikes Peak type, those of the Crip- 
ple Creek type do not have very much micropegmatite developed 
in the fresh specimens, and when it is developed the quartz does 
not show the arborescent and radiate growths so abundant in 
the weathered and metamorphosed rocks, but is present in small 
rounded disks or ovals similar to those described by Romberg.’ 
The plagioclase occurs in small anhedral grains which are 
older than the quartz and the microcline. They are generally 
clouded with alteration products which may be either irregularly 
distributed through the individual; arranged parallel to the 
twinning lamellae; or concentrated in the center with a sur- 
rounding clear zone in similar optical orientation. The twinning 
lamellae, according to the albite law, are very fine and usually 
extinguish almost simultaneously parallel to their composition 
face: 
The other constituents, zircon, apatite, and magnetite, show 
no unusual features and are very sparingly developed. 
Distribution —The granites of the Cripple Creek type are 
most characteristically developed in the area lying to the west 
of a line drawn from Lake George to the town of Cripple Creek 
and thence in a somewhat sinuous line to the waters of Oil 
Creek. Between this line and the volcanic deposits on the west 
is a broad stretch of relatively level country considerably dis- 
sected on its eastern side by Oil Creek andi its tributaries. 
The contacts against the Pikes Peak type are generally 
obscured by the presence of narrow bands of highly metamor- 
phosed schists which were included in the older type and cut by 
=N. J. B. B-B. VIII, 1892. 
