slight
angle to their dip. In fact, all the evidence noted by me during the
last 22 years favours the idea that comparative stagnation to the
liquids circulating in the earth's crust is necessary to the
precipitation of their golden contents. In other words, if the channel
of circulation is unimpeded, and so long as it admits of an equal speed
of circulation for its contents at all its parts, there will be no
deposition of gold in payable quantities, although, perhaps, there may
be plenty of quartz and sulphide. On the other hand, receptacles for
lode material are rich when they are connected with a main channel by a
little channel called a " head " ; this is especially the case if the
structure of the main channel admits of a little slackening of the
speed of circulation near the connexion with the " head." I think that
in situations such as this, where a " tight" part of the channel
follows a wider part, the waters in time eat away, as it were, the
country dividing the side receptacle (full of riches) from the main
channel, and replace the material thus removed with quartz. Then there
appears to the eyes of the miner a foot-wall or hanging-wall, as the
case may he, of book-like quartz, having a great carbuncle of
cloud-like quartz, perhaps 50 feet wide in places, on its side. This
enlargement of quartz being off the line of circulation, the solutions
in it were comparatively stagnant, and thus time was allowed to receive
and
deposit
gold from the main channel. At such points the main channel itself, if
obstructed by floors (including under that term breaks or slides,
cross-course dykes, and ordinary " heads "), or if the walls occur
close together as a "lode track," is rich in gold, which is in the
quartz itself and between the leaf-like layers of quartz. The direction
of the pitch of the richest part would have been arranged by the forces
that arranged the fracturing of the rock-beds.
This
line of quartz lodes on which Hansen's and the Harbridge parties are at
work is worthy of more extensive treatment, and of the services of a
mill on the ground. At no distant date the lode formations of these
ranges must pass through the mills, and mining townships will be
founded where now all is wilderness.
About
half-a-mile to the east of Hansen's line of lode are the remains of
works on a line of quartz formation known as O'Keefe's. Here, in or
about the year 1895, the O'Keefe Brothers, who were alluvial miners
from a place known as Derwent Jacks, near Pitfield, were fossicking for
shallow wash-dirt, when they found in the grass some nuggets of gold in
solid lumps and in tea-lead form. They searched a strip of surface
material along a length of about 200 feet north and south for more
nuggets, and finally put down shallow shafts on it, with a view to
noting how things appeared below the surface. These works brought to
light a narrow channel, \ inch wide, going clown almost
vertically in gold-slate country. It contained oxidized iron sulphide,
and at points where it met with a floor which crosses its line at an
angle of about 10° to the horizontal, it had deposited a thin layer of
quartz. This quartz contains nuggets of gold at and near the point
where the quartz appears to have interfered with the circulation of the
channel
