and moderately charged with pyrites—a
metallic combination of iron, arsenic, sulphur, silver, and gold. The
presence of copper also is indicated. Free gold —that is, gold
uncombined with other metals—is but seldom met with. When it is found,
it is found, as a rule, in quartz near the surface, where atmospheric
influence has been brought to bear upon the metallic deposits in the
stone. Decomposition then sets in, and the metals subject to oxidation
having become resolved, the precious metals, which are unaffected by
the atmosphere, remain as granular or flaky or filmy deposits in the crevices of the rotten and honeycombed quartz, which is called gozzan.*
Captain
G-ifford very frequently crushes the quartz taken from these tunnels,
and states that after having washed it, he almost invariably obtains
colour, or a few specks of gold; quite enough to establish the
auriferous character of these reefs. But assays of samples will always
vary considerably, and can never be relied upon to indicate with any
certainty how much profit may be calculated upon. Working
*
This is the general character of the quartz in this neighbourhood, but
there is a probability that true fissure veins may be reached at
greater depth, where the gold has come up from below unmixed with
pyrites. If so, it will obviously in this condition be much more easily
recovered than from pyritous quartz. Where the gold is free, simple
stamping and washing will suffice; but the amalgamating process is very
tedious, and the risk of loss is greater. Thus, with the St. John del
Bey Company, which has been working on a kind of pyritous ore for many
years, with great success, there is still a certain percentage of loss
which is ascertained by a careful analysis of the tailings.
