Composition:

Petrographic Description:  Typically these rocks are hypidiomorphic with 
granular texture.  Quartz, orthoclase, and plagioclase make up at least 93% 
of the rocks.  Quartz anhedra possess moderate to strong undulatory 
extinction, the orthoclase anhedra are slightly kaolinitized.  Perthite is 
common in the orthoclase with the amount of albite in the orthoclase is 
approx. 8%.  The plagioclase is often sericitized, while the biotite is largely 
altered to chlorite.  The modes for this sample were; 40.4% orthoclase, 
38.5% quartz, 19.7% plagioclase, 1.1% biotite, and 0.3% magnetite.  There 
was no sign of carbonate in thin section, but spectrum and chemical analysis 
both indicate presence of a small amount.

Microprobe Analysis:  The analysis revealed the plagioclase composition to 
be albite, with no more than 5% anorthite.

Chemical Analysis:
SiO2  75.50
CaO  0.35
TiO2  0.21
Na2O  3.5
Al2O3  12.6
K2O  4.7
Fe2O3  1.0
H2O  1.04
FeO  0.24
P2O5  0.02
MnO  0.02
CO2  0.15
MgO  0.23
TOTAL  99.56
