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Association of American Geologists. 185 
Those which were regarded as true veins, were uniformly noticélllte 
originate in the trap rock, but they were frequently traced across the 
superimposed sedimentary rocks, to and including the. red sandstone. 
The direction of the veins across the upper rocks most roqeeaily corres- 
= ponds to the dip of those rocks. 
Dykes of trap, traversing the conglomerate and sandstone, were stated 
| a be of frequent occurrence; but these dykes very rarely cut across the 
strata of the upper rocks, or in other words, they mostly occupy places cor- 
responding to the lines of stratification, for which reason the veins referred 
to, cut across the dykes at very high angles. 
So far as we are enabled to judge from the examinations which have 
_ been made, those veins originating in the outer range of trap hills are the 
“only ones in the district deserving the name of metalliferous veins. Not 
only do the separate veins vary from a mere line to several feet in thick- 
ness, but those traversing the several rocks above the trap, are usually 
very much expanded in their passage across the upper rocks. 
By far the most important minerals contained in these veins are the 
several ores of copper. The metal occurs in a native form associated 
with the grey and red oxides, carbonate and silicate, together with several 
mixed compounds. Sulphuret of copper is exceedingly rare, and pyritous 
per has not been found in what was regarded as a true vein, though 
this last named mineral, associated with the sulpburet and carbonate of 
lead, was noticed in small ramifying veins, in what may perhaps be re- 
garded as a distant portion of the range under consideration. Native sil- 
ver was very rarely seen in the form of specks and strings aemcisiod 
with the native copper. 
Most of the ores of copper occur in the greenstone, Pay gelato ahd 
lower portions of the conglomerate, or at points in near proximity to 
the dykes before referred to, and they are most abundant at, or near to 
the junction of the trap and conglomerate, or in immediate vicinity of the 
dykes, thus nants the general laws respecting the deposits of the me- 
tallic minera 
As the veins I iieade from the trap, the place of the copper is frequently 
supplied by the silicious oxide and carbonate of zinc, together with calca- 
Teous spar, _ latter usually fills the entire vein in its passage across 
the sandston 
The wainainus in those. portions of the vein most rich in the ores of 
copper is chiefly quartz, and this is frequently filled with minute specks 
and filaments of the native metal. 
Dr. H. conceives these to be veins of sublimation, or in other words to be 
simple fissures filled from below by the metal in a vaporous state, and that 
| the compounds had their origin from copper in a native form. The 
conglomerate was stated to have been noticed where the cement consisted 
Vol. x11, No. 1—April-June, 1841. 24 
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