Composition:

Petrographic Description:  Modally the sample contains 57.8% plagioclase,
14.5% orthoclase, 14.4% hornblende, 8.6% quartz, 4% magnetite, and 0.7%
apatite.  The plagioclase generally forms large subhedral grains moderately 
to strongly altered to clay minerals and sericite.   The orthoclase and quartz
are anhedral and interstitial, with orthoclase often altered to kaolinite, and
finely perthitic.  Quartz shows little or no undulatory extinction.  The
amphibole forms subhedral to anhedral crystals which are usually 
pleochroic pale yellowish green to greenish gray, and commonly uralitized.  
The slightly low quartz content of this rock for a granodiorite makes it more 
properly a syenodiorite.  No carbonate was seen in thin section, but both the spectrum 
and chemical analysis indicate the presence of a small amount.

Microprobe Analysis:  The feldspars range in composition from calcic
oligoclase to labradorite (An40 to An60).

Chemical Analysis:
SiO2  56.0
CaO  5.3
TiO2  1.23
Na2O  3.0
Al2O3  15.8
K2O  4.2
Fe2O3  5.0
H2O  1.59
FeO  3.8
P2O5  0.53
MnO  0.33
CO2  0.16
MgO  2.7
TOTAL  99.61
