96 
About i mile east from Mount Cudgewa, along the main ridge, Mildren 
and Nugent’s lodes are met with at about 800 feet below the level of the 
principal lodes on the mountain. As Professor Gregory points out, this 
does not imply that the lodes live for a depth of 800 feet. These lodes 
are in the same granitic rock and run nearly east and west. The northern 
lode is of quartz with felspar and black tourmaline, and a good sprinkling 
of cassiterite through the quartz, and is 9 inches thick. Three chains south 
of this lode is a quartz lode with much black tourmaline; in parts it is 
well studded with cassiterite. Only surface holes have been sunk here. 
These lodes deserve a thorough trial. 
The lodes, though mostly small, .are the most promising yet found in 
Victoria, but whether they can be worked profitably has to be proved. 
This work could be best accomplished by continuing the tunnel for another 
150 or 200 feet in its present direction, and this work should certainly be 
done. The Messrs. Mildren of Berringama have done excellent work in 
opening up these lodes. 
Mr. D. J. Mahony, M.Sc., F.G. S., examined a hand specimen of the 
Mt. Cudgewa rock and reported as follows : — 
The specimen examined was collected by Mr. E. J. Dunn from the 
tunnel which is being driven to intersect the tin lodes at Mount Cudgewa, 
and is a typical example of the undecomposed part of the rock forming the 
top of the mountain. It is a grey-coloured rock of the granite type, 
moderately fine grained and even is texture and consisting of quartz, white 
or greenish felspar and black mica; specific gravity 2.66. The quartz and 
felspar are granular and only a few of the felspars have any distinct crystal 
form. The largest of these, which is simply twinned and appears to be ortho- 
clase, is a quarter of an inch long, but as a rule the felspars are not more 
than half this size. Many of them have a peculiar greenish tint and a greasy 
lustre due to alteration or decomposition. The quartz which is rather less 
plentiful than the felspar occurs in irregular grains of about the same size 
and is of the usual granitic type. The mica is plentiful, and as a rule is 
evenly distributed through the rock, but in some places has segregated into 
small patches. It sometimes has hexagonal outlines but is usually ragged. 
The plates are about i-i6th inch across. There are joint planes through 
the rock in two directions, and along one of these there is a little pryites. 
Under the microscope (rock sections Nos. 1116 and iii6a) the rock has 
a typical granitic structure, and intergrowths of quartz and felspar are 
common. It consists of quartz, orthoclase, plagioclase, and biotite, with a 
little magnetite, apatite, zircon, colourless garnet, brown tourmaline, 
chlorite, and (?) fluorite. 
The plagioclases probably represent more than one species as the charac¬ 
ter of the twinning striae varies a good deal in different individuals. They 
have often sharp crystalline outlines and zone structure is common. Sec¬ 
tions suitable for the measurement of extinction angles are not common in 
the slices, but one section gave symmetrical extinctions at 21 deg., so that 
this rock may be classed with the grano-diorite group. Orthoclase is less 
common and has crystallized after the other felspars and occupies the spaces 
between them. It is sometimes twinned according to the Carlsbad law, 
sometimes untwinned. The felspars are often partly decomposed to a dusty- 
looking mineral (? kaolin) and white mica, and the decomposition often 
begins in the centre of the crystal. 
The quartz is of the usual granitic type, full of minute bubbles and 
small rod-like crvstals. 
