gold
exists in such small quantities, that a gradually-increasing loss
arises upon each ounce of gold produced, from the increased expense of
pursuing the vein deeper.
Gold
mines are, however, found extensively in the primary formations, in
which the metal is sometimes intimately mixed with the rock generally,
or it may be in lodes or veins spreading about like the twigs of a
tree, sometimes thick and sometimes scanty, so that the search for it
is not only tedious, but highly expensive, from the great mass of rock
which has to be reduced to powder in order to obtain a small quantity
of gold. It is for this reason that the gold mines of the
Merionethshire and Wick'.ow mountains are not considered worth working.
Indeed, although gold veins are worked in many countries, it is only in
California that the gold rocks have been found worth working on a large
scale, and even in California the sums spent in the unsuccessful
attempts at rock mining are very large, as some of the English
companies formed for that purpose can testify.
It
is then to the rivers or to the action of water generally that we have
to look for the most profitable supply of gold. Instead of hard rock,
soft sand has to be scratched, and the search is often rewarded—in
Australia beyond any other gold country—with bunches and lumps of the
rich metal, varying in value from a sovereign to 4,000 sovereigns,
while lumps of the value of a hundred sovereigns, or more are common
prizes.
Gold
is again found overlying the diluvial deposits in recent earthy n.
atter, and has been slowly and gradually brought into the valleys and
streams by the action of rain torrents, &c, in the neighbourhood of
auriferous beds; and not always in the neighbourhood of these only, but
gold-bearing rivers are frequently beyond the primary formations. Gold,
under these circumstances, is the mere concentration of many ages, by
the action of water on earthy and ferruginous soils, which for hundreds
of miles may contain traces of gold throughout, but yielding so small a
percentage per ton, that by no known process of extraction can it be
rendered available. Some of the states of North America, Mexico, and
Brazil contain gold under those conditions, but hardly worth the
working; the object being not so much to find where gold exists—for
next to iron it is the most abundantly distributed metal—but to find
where it exists in quantities sufficient to repay the labour of
gathering it.
The
last condition under which gold may be expected to be found is the one
before alluded to, viz., in previously-worked alluvial and diluvial
deposits, in which, from imperfections in working or washing a portion
escapes, which, from its specific gravity, settles in the earthy
contents of the workings and rivers, and as the earthy matter is
annually washing away, while most of the gold remains, after a lapse of
time the working of such localities over again will be found to be
profitable. But as new fields in Australia will be abundant for ages to
come, we need not pursue this matter further.
The
great gold desideratum of our day is a solvent which shall loosen the
metal from the rock without the tedious and expensive process of
pounding, separating the gold from earthy matter with less loss than
is at present the case. The various amalgamating apparatus are too
tedious for poor ores, and unnecessary for rich ones. The well-known
simply affinity of mercury for gold will secure the smallest particle;
but unless water be abundant, and something like 200 grains can be
obtained per ton of earth, it will not yield any profit worth notice.
It
has generally been found that at a distance from the mountains in which
auriferous streams arise, there is a point in which the gold is nearly
an impalpable dust, and that on going up the stream the particles
sensibly increase in size, till at length they assume the appearence of
scales ; higher up still, the metal increases in coarseness, till the
gold is found in its natural roughness as if fresh broken from the
matrix, being more or less interwoven as, it approaches its source. As
it ipproaches this, pieces are found to which
