Composition:

Petrographic Description:  A fine-grained porphyritic rock with a felty
texture, bearing olivine phenocrysts.  The groundmass consists of 
plagioclase, olivine, augite, and chromite with interstitial brownish glass; 
results of the glass analysis are given below.

Microprobe Analysis:  (by Rosalind Helz).  The olivine composition was 
Fo80, that of the feldspar An85 (bytownite).  Titanaugite was also probed.  
Glass composition was:

SiO2  50.54
Cr2O3  0.00
TiO2  4.25
CaO  9.64
Al2O3  12.83
Na2  2.83
FeO  12.60
K2O   0.86
MnO  0.14
P2O5  0.36
MgO  5.58
TOTAL  99.49

Chemical Analysis:  (by John Marinenko, USGS, Reston, VA.)
SiO2  49.11
CaO  12.22
TiO2  1.56
Na2O  1.84
Al2O3  12.96
K2O  0.32
Fe2O3  1.47
H2O  0.04
FeO  8.26
P2O5  0.18
MnO  0.15
Cr2O3  0.13
MgO  11.95
TOTAL  100.13
