ST. LAWRENCE COUNTY. 341 



Stated, has prevented tlie exact determination of the geology at numerous places ; and hence 

 I have been obliged to rely upon cstablislied principles in designating the geology of these 

 points, instead of observations made upon the spot. I trust few material errors will require 

 correction by subsequent examinations. 



In the above remarks in relation to hornblende, it is not intended to convey the impression 

 that it does not occur in tiie soutliweslcrn towns ; it is, however, rather a mineral tlian a rock, 

 and is of frequent occurrence, but more frequently in distinct crystals. A range of gneiss 

 and hornblende, of the ordinary kind, forms the shores of the St. Lawrence river southwest 

 of Alexandria ba}' ; and the same rocks also form the greater part of Wells' island. 



This district difiers also from the gneiss and liornblcnde districts already described. I stated 

 in the preceding pages, tliat the granite of Alexandria, and I may add that of Hammond 

 twelve miles north, is similar to the New-England granite. The same remark may be made 

 in relation to the gneiss and hornblende. They occupy but a few miles of the surface ; they 

 all form low ridges, and never rise higher than moderately elevated hills ; they furnish no 

 interesting minerals, and none of the mines of the nortli are connected or associated with the 

 rocks of this limited district. 



Iron Ores of the Primary District of St. Lawrence County. 



One very remarkable difference in the iron ores of St. Lawrence and Essex or Clinton, is 

 found in the state of oxidation. In the latter counties, though the peroxide often occurs, it 

 does not appear in that distinct state of peroxidation which it does in St. Lawrence ; for liere 

 it is either in fine perfect crystals belonging to the forms peculiar to this mineral species, or 

 else it is in the red massive or pulverulent state. It is impossible to offer a satisfactory ratio- 

 nale of this difference. One of the great features, however, of the section in which this oxide 

 occurs, is the great development of the primary limestone, and I have been disposed to look 

 upon this fact as in some way connected with the differences here adverted to. 



The localities of the specular ores are quite numerous, though but few are really important, 

 and furnish sufficient amount of ore to make it an object to work them. 



One of the most important localities is the Parish mine, in Gouverneur. This mine is in 

 gneiss. The ore formerly formed a hill in a small valley, fifty or sixty feet high, and in cir- 

 cumference twenty-five or thirty rods. The upper or superior part w'as the potsdam sandstone, 

 highly charged with the oxide of iron, and some portions of it with sulphuret of iron. It 

 appeared as if the whole mass of sandstone was raised up by some force applied beneath. 

 Whether this conjecture is right or not, we find on either side the sandstone thrown oft' in 

 different directions, and on each side dipping from the great mass of ore. Now upon the 

 subject of the position of the specular ore when it occurs under this form, it scarcely admits 

 of a question but that the mass has been projected upwards from below. It is true that the 

 oxides of iron do occur interlaminated witli sedimentary rocks ; but the circumstances and 

 condition of the masses of ore in St. Lawrence do not favor at all the theory that they have 



