ECONOMICAL GEOLOGY. 
2S3 
have been developed, which, in a few rare instances, is down to 200 — 300 
feet. 
Many of these quartz veins are in reality beds, as the} T coincide in 
strike and dip with the stratification, whilst an equally great number run 
in every conceivable direction, and dip just as irregularly. 
The greater portion of these quartz veins contain no gold, or only such 
a small quantity that they could not be profitably worked, especially the 
large veins of vitreous and milky quartz. 
Many of the small veins, principally those which contain granular or 
saccharoidal quartz, are rich in gold. 
Some of the large veins, especially those containing much cellular 
quartz, have frequently been found to be the most productive. This cel- 
lular quartz results from the decomposition of pyrite. which once occupied 
the now empty spaces ; leaving them either occasionally quite free from 
iron, or more generally rusty and more or less filled with limonite. 
These, the so called brown gold ores, are the best and most easily worked. 
At a greater depth of the veins,, where the pyrite is not decomposed, the 
gold is so much mixed with heavy sulphurous ores that, with the present 
system of operations, it cannot be extracted with profit ; in many cases 
the gold disappears entirely. 
Most of these gold veins in North Carolina were abandoned, when the 
iron and copper pyrites increased too largely, and before they had been 
wrought deep enough to contain copper ores in paying quantities. 
The gold in these mines is not evenly distributed through the mass of 
the gangue ; the veins often contain entirely barren portions alternating, 
with rich ones, the latter called shoots of ore or chimneys. 
Such shoots are in reality veins inside of a vein, and are frequently 
quite regular in their dip ; the ores at the foot wall are generally richer 
than those at the hanging wall. 
Many gold mines of this description have formerly been worked, and 
many of them undoubtedly are still of great value. 
Many of the quartz veins in the slates, differing in strike and dip from 
the inclosing slate, carry gold, especially those which contain cellular and 
cavernous quartz, associated with limonite, hematite, siderite, pyrite, chal- 
copyrite, etc. 
The gold deposits, which are cotemporary with the slates themselves, 
are of far greater importance than the true gold veins. 
The talcose, chloritic, micaceous or arenaceous slates in which they 
occur, contain portions which are more or less charged with gold. The 
gold in these slate beds, like the slates themselves, is derived from the 
destruction of the older rocks, and has been deposited simultaneously. 
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