QI 
which contain pockets of apatite about the size of the 
fist, evidently a constituent of the rock and not displaying 
banding or vein structure. Apatite-bearing veins cut 
pegmatites near Watt’s pit, on the Lansdowne property 
south of the main road, and in the north-east corner of 
the map area. 
PETROGRAFPHICAL NOTES. 
Silimanite-gneiss—Samples of this rock from the 
northern part of the hill contain a strongly pleochroic, 
brown biotite as their principal coloured constituent. 
This mineral occurs in ragged grains and is often micro- 
poikilitically intergrown with feldspar. Fanlike aggregates 
are also common. Sillimanite occurs in large grains or as 
fine needles, at the boundaries between feldspar individuals. 
Feldspar, including orthoclase and microcline, is an 
important constituent and is often crowded with inclusions 
of fine, opaque needles. Quartz, which is subordinate 
in amount to feldspar, is rich in similar inclusions. The 
accessory minerals include a small amount of muscovite, 
zircon—with pleochroic halos when surrounded by biotite 
—pyrite, leucoxene, and in one case garnet. The pressure 
to which the rock has been subjected is indicated by strain- 
shadows in the quartz and feldspar, and by the incipient 
‘“‘mortel-structure,’ developed more especially in the 
case of feldspar. 
Biotite granulites from the same locality are rich in 
pink garnets which often have borders of ragged biotite. 
Brown, strongly pleochroic biotite, orthoclase and micro- 
cline are the other essential constituents. Micro-perthite 
is sparingly represented, and quartz is subordinate in 
amount to feldspars. Accessory constituents include 
round grains of zircon, a rich sprinkling of dark brown 
rutile and very little apatite and pyrite. Strain-shadows 
are seen in the quartz. Microscopic examination is 
sufficient to determine whether this is an altered sediment. 
or of igneous origin. 
Muscovite-biotite-gneiss from the same part of the hill 
consists almost wholly of micas, the biotite being brown 
and intensely pleochroic. Quartz, a very little orthoclase 
and some plagioclase are also present, and zircon occurs 
as an accessory. 
