Kkx T. Pridkr. 
I OH 
Under tlie microscope the constituents are hornblende, diopside, and 
jdagioclase with accessory (juartz, apatite, and sphene. The hornblende 
and diopside are concentrated into alternate bands (figure lOB) and appear 
to have crystallised independently. The hornblende has a much stronger 
absorption than that described above — it has X yellow-green ; ’N' brownish- 
green ; Z deep bluish-gi’een : and absorption X Z ^ Y ; ^ ^ ^ I ■(>74 ; and 
Z/\c — IH°. The diopside is in irregular cf|ui(limensional grains to 0-5 mm. 
diameter. They have no <lefinite orientation, tlie longitudinal cleavage being 
arranged at various angles to the schistosity, indeed often normal to it. 
This mineral is a pale greenish variety with the (110) cleavage well develof^ed, 
Z/\c — 42°, indicating the considerable iron content. The dioi)side is- 
idioblastic towards both the plagioclase and hornblende. F^lagioclase forms. 
Fig. 10. 
Pyroxene-plagioclase amphibolites. 
A. Coarse xeiiolith in Lower Gneiss. Constituents: diopside 
(dotted), hornblende (]>alor coloured at junction with diopside), 
slightly turbid plagiocdase, quartz. 
B. Fine banded variety interbedded with (]uartzite. Constituents: 
hornblende in well defined bands, diopside (dotted), plagioclase. 
approximately 30 per cent — it appears in two generations (1) a very turbid 
indeterminable variety clouded with secondary fine granular zoisite — this 
variety is more or less confined to the hornblendic bands ; (2) a clear fresh 
]‘)lagioclase associated with the diopside bands. Fine lamellar twinning 
is occasionally develo])cd and the small extinction (2° - 3°) in sections X 010 
indicates an oligoclase. Slight normal gradational zoning is notic'cable in 
some grains. 
Sphene and rare apatite are the only accessories. Iron ores are absent. 
Another specimen belonging to this group has an *' augen ” structure — 
the augen are of diopside aggregates set in a plagioclase amphibolite ground 
in which the felspar is heavily saussuritised. 
A specimen taken from the iipper contact of the hornblende schist with 
the quartzite at a point 132 chains E. and 229 chains S. of datum, shows a 
