124 
Rkx T. Prider. 
Xonoliths of various types are described : — 
(1) Eulysitic types developed from banded iron ores, probably sideritic 
and other carbonate types. 
(2) Grossularite-diopside-qiiartz rocks derived from impure argillaceous 
limestones. 
(3) C’ordierite-anthophyllite rocks and relate*d types deri\'ed from 
ultrabasic igneous rocks. 
(4) Amphibolites, resulting froTU the reconstitution of basic igneous 
1 ‘ocks. 
\^.~ --The Younger Igneous Intruslves. 
(1) The Granites. 
The later non-foliated granites are confined to the south-west part of 
the area when* tliey are intrusive into the series described above. The gran- 
ites are cut by later pegmatites, aplites, and cpiartz veins, which often pene- 
trate the nearby metasediments and which are considered to be the source 
of the auriferous deposits found in the mica schists close to the granite. 
The granites are always medium to coarse even-grained, remaining coarse- 
grained right to their contact with the metamorj^hic rocks, indicating that 
intrusion took place at some depth into already heated sediments. There 
is no sign of the porphyritic and foliated structures seen in the older granites 
occurring as bands in the Jimperding Series. 
The later granitic intrusions are represented by thrf'e phases, which may 
may be described briefly as follows : — 
(u) The )iormal granites are coars(* textured rocks consisting of (piartz, 
slightly perthitie microcline, sericitised oligoclase (Ab 4 Aii 2 , often 
with zonal alteration), abundant myrmekite, irregular chloritised 
biotite flakes with intergrowths of epidote, and accessory apatite 
and sphene. In their mint'ralogical composition these rocks 
are \'ery similar to the older granite gneisses described above. 
(6) Garnet-nniscovite granites are even, fine to medium grained, allo- 
triomorphic granular structured rocks made up of quartz, slightly 
perthitie microcline, oligoclase and muscovite, with accessory 
pink garnet {altered along irregular cracks to greenish biotite) 
and a little brownish biotit(\ These represent a hypabyssal phase 
of the granite and occur as dykes in the metamorphies close to 
the main granite mass. 
(c) Pegntatites, garnet aplites, and later quartz veins represent the final 
phase of the granite intrusion. They are found in dykes and 
\eins in botli the granite and adjacent metamorphies. The peg- 
matites are coars(* grained microcline and muscovite bearing types, 
in which the presence of molybdenite, columbite, and beryl have 
been noted- — the two latter by Simpson (personal communication). 
The garnet aplites are the tine grained equivalent of the garnet- 
museovite granit(*s. The prevailing texture is fine equigranular 
granitic, and the constituents are quartz, microcline, and oligo- 
clase with accessory biotite (rare) and small pink gai'uets. The 
aplites often form a part of the pegmatite veins. 
WJiite quartz veins, representing the final ultra-acid ])hast* of the 
granite, are fairly numerous in the metamorphies close to the 
granite. A flat di]3ping f[uartz vein in a roof pendant of mica 
schist in the granite has been proved to be auriferous, a test parcel 
(50 tons) of this ore mined several years ago yielding 15dwt. 
gold per ton. 
