of
quartz impacted, and have generally an obscurely granular
appearance—more indeed like quartzite than vein-quartz, and in many
places, as already stated, they exhibit a tendency to become grantic,
large plates of muscovite and apparently a hydrated muscovite in
smaller' plates, with here and there a little felspar giving them a
character which separates them at once from the well-known rich
pyritous veins near Devala. Some of the massive quartz near Moopenaad
and Vellirymulla micacised and in structure simulating granite, or
partaking of the character of the country rock, might well be supposed
to be bedded and not vein-quartz and contemporaneous with the gneissoid
rocks with which it is associated. There was no true quartzite seen in
these places, but it may be conjectured that the induration and
alterations of compositions and structure, which have resulted in the
formation of the foliated gneissoid rocks would not be without
influence on purely silicious granular interbedded masses.
From
the larger (true) veins " leaders" are thrown off, most commonly to the
westward. The leaders usually dip at a low angle, but in some places
they are so large and of such a form as almost to give the character of
"saddle" reefs to the masses of quartz.
The
ordinary " casing " of the reefs is a talcose schist (easily separable
into thin laminae) with oxide ef iron and the minerals ordinarily
therewith associated; and gold in small flat particles, visible to the
eye, is not rare in the casing. The casing of many of the large
auriferous reefs is quartzose and ferruginous, rudely laminated and
with scales of ripidolite and talc scattered through the mass.
The
average thickness of the true quartz veins is about five feet. Some are
less than two feet in thickness, and others again exceed fourteen feet.
The greater number, however, vary from four to seven feet. The
direction of the veins is usually N. 30° W.—S. 30° E., and some are
nearly due north and south; and the dip, though nearly always easterly,
is irregular. On the summits of the steep hills the veins are commonly
almost flat or with a very slight dip to the eastward, but at a little
depth from the surface the dip is, as might be expected very different.
It is not seldom as much as 30°, 400, and 6o°.
These
sudden variations may be due partly to the changes produced on the
surface by the heavy rains which fall yearly. Much decomposed and
almost solid rock is moved in masses, and "the action of gravitation on
substances loosened by weathering, or the ' weight of the hill' as it
has been called, would account for the difference of dip as measured
near the surface and at some depth from the surface.
The
direction or strike of the quartz veins is, in a district like the
Wynaad, broken up, as it is, into rounded hills of varying height not
easy to trace, unless regard be had to the elevation of each point
where an outcrop of quartz is seen. An outcrop on a hill is thrown to
the westward, and the same reef outcropping in a valley is necessarily
eastward of the line which would appear if the ground were of the mean
level.
It
is not yet possible to say what number of separate veins of quartz
there are in the area which has been examined, but there are at least
two hundred outcrops—not necessarily distinct reefs.
From
Moopenaad to Cherambadi, a distance of eleven miles and-a-half by the
road, twenty-three outcrops were observed, many of them indicating
reefs of great thickness; from Cherambadi to near Nadukani in a
straight line south-earterly, twelve miles, there are at least eighteen
separate veins; and east and south-easterly of Devala the reefs are
from 5, 55, ?, 10, 16 and 23 chains apart.
IHween Moopenaad and Cherambadi the rocks are in places arenaceous.
Distribution 0/ Gold.—As
will be seen from the detailed reports which follow, gold is almost
universally distributed throughout the soils and quartz veins of the
Wynaad. It occurs also in the sands and soils both on the east, west,
north , and south.
In
South-Fast Wynaad, on washing a few dishes of the surface-soil
anywhere, a few specks of very line gold will be found; in the vicinity
of the reefs
