COMPARATIVE RICHNESS OF VEINS. 
161 
COMPARATIVE RICHNESS OF THE UPPER AND DEEPER 
PARTS OF THE VEIN. 
§ 96. The opinions of miners, as well as geologists, do not 
agree on this question. The facts sustain apparently the doc¬ 
trine that the yield of gold diminishes where the vein is beneath 
water. When the facts, however, are carefully examined, 
they are not so decisive of the assumed position. The mine 
which is of all others most reliable in North Carolina, is the 
Gold Hill mine. Its depth is about five hundred feet; the vein 
quartz, bearing the sulphurets of copper and iron, and the rock, 
a greenish slate. The upper forty or fifty feet of the vein was 
decomposed, and of course the gold easily obtained. Different 
companies had leased parts of the vein. One company 
worked upon a level between one and two hundred feet from 
the surface; another company worked a three hundred feet 
level down to four and five hundred feet. Now, while the vein 
did not yield profits at all large at the upper level, the lower 
was very profitable; even twice the amount of gold was 
obtained in the deepest part of the mine. 
The opinion that a gold mine is less rich in the lowest levels 
or below, arises from the state of the metal, or from its com¬ 
bination with the sulphurets; and experience has proved in 
thousands of instances that it is extremely difficult to separate 
the gold by the mechanical processes usually resorted to. After 
the ore has been subjected to one operation, and all the gold 
apparently obtained from it, and this fine material is allowed 
to remain a year or two exposed to the air, and then worked 
again, it will usually yield by the second process nearly as 
much gold as was obtained by the first; and so the same ore 
may be worked five or six times, and made to yield profitable 
returns of gold. These facts are especially applicable to the 
auriferous sulphurets. It appears then from experience in North 
Carolina, that the auriferous veins are equally rich below and 
above water, to use the common comparison, and that there is 
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