Composition

Petrographic Description:  A slightly deformed metamorphosed norite 
consisting of large plagioclase anhedra (30%), occasionally showing 
undulatory extinction, bent twin lamellae and granulation.  The mafic phase 
(originally pyroxene) has been altered to a pleochroic green, prismatic 
amphibole (60%).  The opaque anhedra (approx. 4.6%) are frequently 
aligned along former crystallographic axes of this pyroxene phase.  Minor 
quartz (2%) was also noted.

Microprobe Analysis:  Microprobe analysis revealed the amphibole to be a
hornblende, probably tschermakite or hastingsite, with relatively low soda
(1.5% by weight).  The plagioclase ranged from andesine to bytownite 
(An45 to An72), with the groundmass more calcic than the coarse 
plagioclase grains, which is unusual.  An opaque phase probed proved to be 
ilmenite summing to 92%, with the balance probably made up of chromium.  

Chemical Analysis:
SiO2  48.42
CaO  4.96
TiO2  2.52
Na2O  2.87
Al2O3  19.66
K2O  0.27
Fe2O3  2.63
H2O  1.15
FeO  7.09
P2O5  0.03
MnO   0.09
MgO  10.83
TOTAL  100.52
