260 
New Chum Railway and Victoria Reef Mines. 
B. Specimens from the Deeper Levels (3860 feet to 4.025 feet). 
An examination of one of these slates shows it to be remarkably 
like that already described. The hand specimen is dark grey in colour, 
easily scratched with a knife, giving a light grey powder, and distinctly 
cleaved. None of the minerals can be distinguished with a pocket lens. 
Some infiltrated calcite can be seen along one of the cleavages. Under 
the microscope it is seen to consist almost entirely of sericite, with 
chloritic material, clay-slate needles and carbon, as before. 
Another sample is a much crushed rock, in which all trace of the 
regular parallel cleavages is lost. Cleavage still! exists, but the planes 
are much bent. The colour is dark. greenish-grey, the lustre silky, and 
the grain very fine. In places, small micaceous scales can be observed. 
The face sliced for the microscope section shows how the variously 
coloured bands have been crushed and folded together. The microscope 
shows it to be a very fine-grained sandstone. Many of the quartz grains 
show a “wavy” extinction, due to pressure. The ground mass is similar 
to that in the sandstone already described. 
A slate from the 3,900-feet level of the New Chum Railway mine is 
something like the above, but has a rather more silky lustre. Some of 
the cleavage planes are puckered into minute wrinkles. Through the 
centre of the slate there was originally a thin band of sandstone. This 
has been crushed into lenticular pieces, round which the slate has, by the 
pressure, been forced to flow. The microscope shows that the slate is 
similar in mineral composition to those already described. The lines 
along which shearing has) taken place are darker than the rest of the 
slide, and are often thrown into minute wrinkles. They appear to have 
been formed after the sericite. The quartzite occurs in patches entirely 
surrounded by slate, and consists of grains of quartz and a few pieces 
of plagioclase set in the usual paste. Some of the larger quartz grains 
appear to be of secondary origin. For instance, in one case a well formed 
crystal of pyrite is surrounded on three sides by the same quartz grain, 
and in another a group of carbonaceous spots lies partly in the groundmass 
and partly within a quartz vein. Some of the grains, which appear to 
consist of a single piece of quartz, are shown by polarized light to be 
composite. 
The remaining specimens are quartzites. They are grey in colour, 
and moderately fine-grained. The fracture is rather .splintery, and leayes 
a face with a vitreous lustre, due to infiltration of quartz ; but the ori¬ 
ginal grains can still be seen. The microscope shows that most of the 
quartz grains are sub-angular. They contain great numbers of fluid 
cavities, and sometimes small zircons, also minute prisms of some other 
mineral, and occasionally hafr-like inclusions of extreme thinness, which 
may be rutile (Hutchings)*. Some of these grains are crushed into a 
mosaic, or give a “ wavy ” extinction. Here, again, there is evidence 
in the relation of the quartz to the pyrites that the quartz-grains are not 
all primary, and. in addition, a flake of original muscovite is partly 
enclosed by one of them. There are also some plagioclase fragments 
present. One gives an extinction of 12 deg. in the 001-100 zone. 'They 
are polysynthetically twinned and undecomposed. Some rounded grains 
of a colourless or yellowish mineral, with an extremely high refractive 
index, occur occasionally. It may be rutile or anatase. In addition, 
* C'ays, shales, and Slate?. —Geol. Mag.. 1896. 
