Composition:

Petrographic Description:  The sample consists of 47.9% orthoclase, 35.2% 
quartz, 14.6% plagioclase (of which 6.6% is perthitic), 1.4% biotite and 
0.8% magnetite.  In these rocks the quartz anhedra show moderate to strong 
undulatory extinction, the orthoclase anhedra are often finely perthitic and 
slightly kaolinitized.  The plagioclase often show sericitic alteration while 
the biotite may be altered to chlorite.  The thin section did not show any 
carbonate, but the spectrum and chemical analysis both indicate a trace is 
present.

Microprobe Analysis:  In this sample all the plagioclase probed was pure 
albite.

Chemical Analysis:
SiO2  75.10
CaO  0.19
TiO2  0.18
Na2O  3.6
Al2O3  13.0
K2O  5.5
Fe2O3  1.3
H2O  0.73
FeO  0.18
P2O5  0.01
MnO  0.02
CO2  0.05
MgO  0.05
TOTAL  99.91
