Composition:

Petrographic Description:  The sample consists of 37.6% orthoclase, 36.1% 
plagioclase (of which 11.3% is perthitic), 23.2% quartz, 1.9% biotite, and 
0.9% magnetite.  The quartz in these samples is typically undulatory, the 
orthoclase is frequently perthitic and slightly kaolinitized, while the 
plagioclase is often sericitized.  There was no sign of carbonate in thin 
section, but spectrum and chemical analysis both indicate presence of a 
small amount.

Microprobe Analysis:  The plagioclase phases proved to be pure albite.

Chemical Analysis:
SiO2  69.1
CaO  1.1
TiO2  0.42
Na2O  4.0
Al2O3  15.2
K2O  5.2
Fe2O3  1.9
H2O  1.27
FeO  1.0
P2O5  0.16
MnO  0.03
CO2  0.19
MgO  0.55
TOTAL  100.10
