The A B C of Mining: A Handbook for ProspectorsBramble, Charles A.
Science
The A B C of Mining: A Handbook for Prospectors
Bramble, Charles A.
Mining engineering; Prospecting
On account of the wonderful discoveries in the Canadian Northwest and
in Alaska, the eyes of thousands are turned towards those fields.
Wonderfully rich placer ground has already been found and there can be
no reason to doubt that very much larger areas remain unproved. Where
this gold comes from is an open question; geologists, mineralogists
and chemists, not to mention mining engineers and practical
prospectors, have disputed over the source of the gold already found,
but it must be confessed that there are almost as many theories as
there are disputants. Could it be known with certainty how and under
what conditions the gold got where it is found, the problem of seeking
for it might be made easier. Unfortunately this is not the case, and
all prospecting for the home of the precious metal is more or less a
groping in the dark. We do know that the heaviest particles of gold do
not travel far from where they were first deposited, because gold is
so enormously heavy--its specific gravity being about nineteen times
that of water--it seeks the bottom of the stream and stays there. It
is not an invariable rule that the gold increases in coarseness as the
stream is ascended, but it is a very general one. On some rivers rich
and poor stretches of gold-bearing gravel succeed one another as the
explorer makes his way up or down stream. This is difficult to account
for, but in many cases is believed to be caused by the modern river
robbing the bed of some one or more ancient water-courses whose beds
crossed the valley of the present stream. This may or may not be the
case. We only know that the miners who found coarse gold on the lower
regions of such rivers as the Frazer were miserably disappointed when
they reached stretches near the source and found nothing but flour
gold. This same feature has been noticed in some of the Alaskan
rivers. It is quite within the bounds of probability that no very rich
quartz veins exist in Alaska. It does not follow from the richness of
the placers that the gold is derived from very rich quartz lodes,
because this amount of gold may really represent the product of a vast
amount of rock that has been ground to powder and washed away in the
course of ages. The gold would not travel far, and the deposits being
unearthed to-day have been accumulating in these northern streams
since the world was young; water-courses are nature's ground sluices.
Public-domain text, read in full here on John Shaqi.
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