75 
Metam Orphic Bockf^. — The gneisses occur as broken spurs 
and ridges, extending far outward into the sandy plains. On 
the north their character is granitoid and foliated, the planes 
of foliation striking north-easterly. The rock is character- 
ised by bands of quartz and the presence of secondary mine- 
rals in more or less distinct layers. 
North of Mount Davis outcrops of hypersthene-bearing 
granulite, which trend slightly east of north, present splen- 
did examples of spherulitic weathering {KugeUrje Ahsonder- 
ung). This rock is compact and granular, with little or no 
evidence of foliation on freshly fractured surfaces, though it 
is apparent on weathered faces. The rock has a peculiar 
olive-green waxy appearance.* 
The most westerly exposure of the Gosse's Pile Spurt 
consists of gneiss, which is normal, though quartzitic, the 
quartz occurring in the form of elongated lenticles, and the 
mica as small flakes in regular layers of no great thickness. 
The rock is thickly studded with red garnets f Almandine ). 
This class of gneiss predominates in the Tomkinson Ranges, 
it being also met with south of the main range. 
Veins, etc. — Non-metalliferous quartz veins of a bluish 
tint and a shattered glassy character are fairly plentiful. 
They are usually seen in direct association with diorite dykes. 
The Miirru Yihjah Outcrop. — This outcrop, which was 
stated to be auriferous, skirts the northern foot of the Mount 
Davis chain for some miles in a westerly direction (W. 20"^ 
N.), with a prominent escarpment facing the north. The de- 
posit consists of a fresh-looking, highly-siliceous rock, vary- 
ing from an impure siliceous ironstone through chalcedonic 
and semi-opaline varieties of quartz, the chalcedony often 
occurring, encrusting, drusy or slightly stalactitic, or per- 
vading the rock as irregular planes of infiltration. The silica 
has been tinted by mineral salts in solution, the colour rang- 
ing from a rich brick-red through pale yellow to a bright 
green (chromium). Small, irregular cavities exist in the 
rock, which are either coated with a drusy form of quartz or 
filled with haematite, compact to cellular. The rock breaks 
with a conchoidal to sub-conchoidal fracture, and small frag- 
ments, the result of weathering, cover the adjacent slopes and 
* Mr. G. W. Card, of the Goological Survey of New South 
Wales, who examined a section of this rock for me, writes that 
the hypersthene is not very abundant, and is of a deep colour. 
Apatite is present in noticeable amount. The bulk of the rock 
consists of granular quartz and felspar. Granulitisation and re- 
crystallisation are not complete in the case of the felspar, residual 
portions of which may still be seen. 
t Compare "Gosse's Pile Hill is of grey granite, with diorite, 
, . ." W. R. Murray, op. cit., page 17. 
