292 
GEOLOGY OF THE SECOND DISTRICT. 
northeast, dip seventy degrees M'^est-northwest. At a distance of half a mile from the main 
mining ground, in the direction of its strike, an opening has been made, which, has disclosed 
ore of a quality similar to this ; thus furnishing a fact, showing the probability that this vein 
is extended thus far in this direction. 
All the veins have been worked at different periods. The old blue vein was necessarily 
given up, in consequence of the falling of all the western wall for a width of six rods, and 
nearly the whole length to which it had been worked. The veins are called after the color of 
the ore : the first has already been given ; the second is a black variety, having a dull black 
color, but still it gives a brown or reddish brown streak, showing that this also is highly 
oxidated, a fact which would by no means be suspected from the color of the ore. This vein 
appears to be equally pure as the blue; if any thing, it contains less quartz, and for aught 
which can be observed, it is as good. The remaining veins furnish a grey ore : this color 
arises from an intermixture of grey quartz; and the ore, besides giving the red streak, is 
brownish upon the outside. All the veins, therefore, of the Arnold hill, are peroxides; and 
being quite pure, and free from earthy matters, they may be worked without washing or any 
other separation. The grey ores contain the greatest amount of quartz, which is the only 
substance of a foreign kind contained in these veins ; and as experience has proved, it forms 
,the most favorable flux for the perfect reduction of the magnetic oxide. 
The Arnold ores are easy to reduce ; the iron is tough and soft, and is very much employed 
for nails, and all those articles where tenacity is required, and where softness is not an ob¬ 
jectionable character; for wagon tire, though it is essential that the iron should be tenacious, 
yet it wears out too rapidly ; neither is it so valuable for chains as a harder iron. This iron 
was at one time manufactured into cables; but for some cause, it was acted upon by sea 
water more than the English cables, and hence became less saleable, when the business was 
abandoned. 
The four veins upon the Arnold hill are in proximity to each other, being separated only 
by a few feet of rock. The width of the black vein is from three to eleven feet, and that of 
the grey veins from two to eight. The quality of the ore furnished respectively by each is 
very similar, and the products of reduction nearly the same; preference, however, is given 
to the old blue vein. 
In the progress of working them, several dykes have been encountered, which cross them at 
various angles; and in one instance where the- dyke is oblique to the direction of the vein, it 
has produced a shift; that is, the portion included by the dykes has been carried the width of 
the vein to the east. This remarkable change I have illustrated in figure 76. Those dykes 
which cross the veins at right angles, have produced no change or shift; while those which 
are oblique, have carried the veins several feet to the east. 
