1 10 APPENDIX 



of veins by molten matter from beneath, supports the same view, and in this case we see 

 the hill of breccia and beneath the vein. It would be interesting, could we establish this 

 view of the origin of this peculiar rock. This is (juitc apparent, when we take into con- 

 sideration the multitude of these lirecciated beds along the eastern limits of the Taconic 

 system. They range nearly in a line running through Berkshire county, at the western 

 base of the Green mountains, and northwardly into Vermont. The question will not fail 

 to suggest itself to every inquisitive mind, whether these beds are all connected with veins 

 beneath. The question of their origin then assumes a practical importance, and is wortliy 

 of being followed very carefully out to its full solution. If such a result should be ob- 

 tained, it will open an inexhaustible source for this kind of ore, which is usually of an 

 excellent quality, and easy to smelt. It is, however, proper to stale, that the quartz rock 

 in which this vein appears in Adams, is a hard rock to blast ; and it is possible that the 

 expenses, from this cause alone, of obtaining the ore, might be so great as to render these 

 veins useless. Much undoubtedly would depend on liieir width : if wide enough to be 

 quarried without rendering it necessary to lilast the rock itself, tlien there would be no 

 difficulty in working these veins. The matter nmst remain undecided, until some of them 

 are opened and worked. 



The position of the veins of limonite adjacent to the primary of the Green mountains, is 

 analogous to those of Jefferson and St. Lawrence counties, where the specular iron, both 

 in its earthy and crystalline state, appears in veins connected both with the primary below 

 and the potsdam sandstone above. In both cases the veins are found only in thin parts of 

 these sandstones, and near or adjacent to primary rocks. It is curious to observe, how- 

 ever, that in one case, the iron is in a state of peroxide pretty uniformly, forming the 

 specular oxide, and I believe without exception ; and in the other, it is the hydrous per- 

 oxide, constituting the mineral called limonite. The former does not form a breccia with 

 the potsdam sandstone, and we find a different association of minerals also in each of these 

 cases. With the specuhu- ore, we find serpentine, barytes, crystals of quartz, cacoxenite, 

 etc. ; and with the latter, gibbsite, allophane, manganese, and white carbonate of iron. 

 The gibbsite and allophane are minerals of secondary formation, and, so far as observation 

 has extended, they are not found in the veins of limonite. Distinct and irregular veins, 

 however, of the latter mineral, are not new to mineralogists. Thus a few veins, a foot in 

 width, traverse the gneiss of Dekalb in St. Lawrence county. The same occurs near 

 Crownpoint, and indeed a thin vein has been found in the calciferous sandstone in Georgia 

 (Vermont) . A practical remark is suggested by the position of these veins, namely, that 

 their place is near or adjacent to primary or igneous rocks ; or it is here that they are 

 accessible, and reach the surface, though it may not be at all improbable that ihey are 

 frequent in other situations, but concealed by a great thickness of sedimentary materials. 



I take this opportunity to add a few additional remarks on the quartz rock itself. Some 

 geologists of eminence have maintained that this rock belongs strictly to the Primary sys- 

 tem ; that it is of the era and age of the gneiss, with which it is sometimes apparently 



