GRANITIC ROCKS OF PIKES PEAK QUADRANGLE 235 
TABLE If. SHOWING RELATIVE SIZE AND DEVELOPMENT 
Pikes Peak Summit Cripple Creek Fine grained 
Quartz 
SIZe yar rorctsmsleher: Se Om 
average m |i 24am Raye -3m 
NOMEN 6a dsoo oc irregular spheroidal irregular irregular 
Microline (Phenocrysts) 
SIZE ee casioeiate 6" X 3” to 25X15 to TES 
15x30", A ae 
20 X 30™™ as 
INGIAT 65 bade 00 well developed | well developed | well developed 
Microline (Groundmass) 
SIZ ieleriers © aisle HOC Geet DK (Og i <aperten nox gee 
ING 6 o.06 000 irregular irregular irregular irregular 
Biotite 
SWWAS <6 Giecgraee BA I-2™m ra o0.5-1™™ 
Mode of aggrega- 
LKR 50.6 oeNatont single and ag- | single and ag- | single and ag- | single or aggre- 
gregate gregate gregate gate 
Texture 
Coarseness ...| coarse Medium to fine } medium fine 
Arrangement ...| granular to granitophyric saccheroidal to | granular 
porph. gran. orthophyric(?) 
Mode of occur- 
HENGS cune coae large masses small masses large masses small masses 
and dikes and dikes 
The accompanying tables show at a glance the marked simi- 
larity in the mineralogical composition, and the equally marked 
diversity in the textural relations presented by the different 
types. 
different types is no more than that due to the presence of occa- 
The diversity in the mineralogical composition of the 
sional orthoclase, hornblende, sphene, muscovite, or epidote in 
specimens collected over an area of more than nine hundred 
square miles. 
thitic intergrowths to be common in the fresh granites of the 
These types, it is true, show well developed per- 
Pikes Peak type and wanting in the other types; while fluorite 
and micropegmatite are prominent in the rocks of the Summit 
type and unusual in the rest of the unaltered granites. The most 
striking, most constant, and most characteristic differences 
between the types are, however, in the relative and absolute size 
