The
gold and sulphide appear to have been widely distributed through the
slate layers, and were there precipitated on the "leaves" of the slate,
along " head " planes, and at junctions of some " heads " with larger,
more extensive " heads," which meet each other at right angles.
This
class of deposition is best developed at points where a " head " plane
has cut through a layer of slate, at about right angles to the "
underlay " of the slate, especially if there happens to be a layer of
quartz from a quarter of an inch to, in some instances, 2 inches thick,
lying on the " head." The deposition of gold especially occurs along
the head plane, where it is in contact with a layer of slate,
especially where there is a little depression, or slight " bump " on
the head plane. This feature favours the idea that obstruction to
circulation in the earth's crust is essential to deposition of gold in
payable quantity.
In
some instances there is a lode of quartz, say 2 inches wide, in the
slate layer. This occurrence is to be seen in places as a mere thread
of sulphide. It occupies a main channel, however, and it deposits its
gold only when the structural arrangement of the rock fractures
produces obstructions to the channel's circulations which allow time
for the precipitating agents to act. Thus arise the patches "along
floors which run across the slate layers.
Indeed,
these instances of deposition are but examples in miniature of the
varying but never-ceasing action which proceeds, in association with
the circulation, in the zone of the earth's crust known to geologists
as the " zone of fracture."
It
is about four years since mining was commenced on this class of
formation in this field, and since then many thousands of ounces of
gold have been obtained by following " floors" associated with slate
layers. " Loaming " is the practice followed in locating the favoured
lines.
To
be a good "loamer" one must have a good knowledge of surface features
likely to overlie the gold-bearing deposits, and he must have unlimited
patience and perseverance. The " loamer " moves on the assumption that
the surface of the ground was much higher in the past than it is at
present, and that gold-bearing lines, since worn down, have left a
concentrate of their gold in the soil nearly over their worn-down edge,
or scattered along the line of the gold-bearing deposit, or below it in
small trails down the side of a range.
He
starts low on the range or one of its spurs, and takes a shovelful here
and there until he locates a " colour." Having a trail, lie continues
to sample, higher and higher, turning this way and that, always
following in the direction suggested by dish prospects until he gets,
in many instances, above the line of gold. Then he turns back again and
samples more carefully, till at last he strikes a pocket in the clay
containing a great many ounces, or a pennyweight or two of gold. This
gold was gathered on a floor which formerly existed far below the
surface but now is situated but little below the grass, in consequence
of the wearing down of the earth's surface.
This
process of locating a patch and a floor in association with an
"indicator," as the miners call these gold-bearing slate bands, may
occupy weeks of time, but the genuine loamer is full of perseverance.
He works on till he runs a trail to its head. Of course, there are good
and bad loamers, and, judging by the pick-marked aspect of parts of the
mountains, indicating many half-hearted attempts to " run a trail " to
its head, the Pyrenees mountains must have been tried by many beginners
in the art of loaming.
