USEFUL MINERALS. 589 



are obviously the result of the heating and oxidation of a part of the 

 carbonate of iron, and this process may be seen, on minutely examining 

 the vein, to have extended itself from the walls of the smallest fissures. 

 bthly^ The action of heated waters passing through its crevices, and 

 depositing sulphate of barytes and brown hematite. 6//((y, The influ- 

 ence of the air and surface waters in changing large portions of the 

 superficial contents of the vein into ochrey hydrous peroxide of iron. 



It is, however, to be observed that this deposit might be accounted 

 for on the supposition that a bed of iron ore and carbonate of lime and 

 magnesia, similar to those occurring elsewhere in the Upper Silurian, 

 had been so softened and altered by heat as to penetrate in vein-like 

 forms the surrounding rocks. Sir W. E. Logan has shown that 

 phenomena of this kind occur in the Laurentian regions of Canada. 



This deposit is evidently wedge-shaped, being largest and richest 

 on the surface of the highest ridges. It contains, however, an immense 

 quantity of valuable ores of iron, though its irregular character opposes 

 many difficulties to the miner. Difficulties have also been found in 

 smelting the ore to advantage ; but these are often incident to the 

 first trials of new deposits, to which the methods applicable to others, 

 of which the workmen have had previous experience, do not apply. 

 It is believed, however, that these preliminary hindrances have 

 been overcome, and that the mine has now become highly profitable 

 to its proprietors. I quote the following estimate of the value of 

 the deposit from the elaborate Report of J. L. Hayes in 1849. It 

 has been fully confirmed by experience : — 



" From the descriptions which I have above given, it is evident, 

 that although the unlimited extent of the ore at any particular point 

 can only be determined by working the deposits, yet an immense field 

 is open for explorations and working. 



" Although it is quite probable that an abundant supply of ore will 

 be found upon the west bank of the river, at a price which will not 

 exceed two dollars to the ton of iron ; if this should not be the case, 

 an ample supply can be furnished from the other localities at an expense 

 which, including raising and hauling, could not exceed four dollars to 

 the ton of iron. I would advise the opening of the veins at difi'erent 

 points upon the line, to determine the cheapest point for mining, and 

 the ores wliich can be used most advantageously. If this is done, 

 the price of the ore cannot be fairly set down at the sum for which it 

 can be obtained from the nearest locality, but at an average of tlie 

 prices of the ores from different localities, delivered at the point 

 selected for the furnace. This may be estimated at three dollars to 

 the ton of iron. 



