4 ECONOMICAL MINERALOGY. 



Commencing with the southern part of the State, we first observe beds or veins of magnetic 

 iron ore crossing the hne between New-Jersey and New-York, at or near the southern extre- 

 mity of Orange county ; and they occur abundantly in various parts of the primitive ranges 

 which traverse this county in a northeasterly direction. Crossing the Hudson, this ore is found 

 in abundant, though less numerous, deposits in Putnam county. 



In proceeding from these primary ranges in a nortliern direction, the magnetic iron gives 

 place to other ores of this metal, until we reach the granitic ranges of Saratoga, Washington, 

 Warren, Herkimer and Lewis ; in each of which counties, beds of the former ore are found 

 of greater or less extent. They also abound in various parts of Hamilton, Essex, Clinton and 

 Franklin counties, while they are rarely met with in Jefferson and St. Lawrence. 



Before proceeding to describe the particular localities of this important ore, it may be proper 

 to remark, that so far as my observations extend, it possesses great similarity of composition 

 as weU as of combination. In a great majority of instances, it is both mechanically and che- 

 mically mixed with silica. In several cases, however, other minerals are associated with it, 

 as hornblende, feldspar, pyroxene and mica. It sometimes also contains small proportions of 

 titanic acid, a fact which is proved not only by chemical analysis, but by tlie small crystals of 

 metallic titanium which are found in the slag produced during the process of reduction. Sul- 

 phur, in the form of iron pyrites or bisulphuret of iron, is moreover a common associate of the 

 magnetic iron ore, a fact of importance to the iron master, as it often occurs in such large 

 proportion as to prove injurious to the resulting iron. In such cases the exposure of the ore 

 to the combined agency of air and moisture, causes the decomposition of the pyrites, and the 

 consequent production of sulphate of iron, which is at length entirely removed by rains. A 

 fine illustration of the correctness of this remark will be found in a heap of ore which was 

 some years since raised from a part of the great Philips vein in Putnam county, and which 

 has thus been freed from the iron pyrites originally associated with the ore in such a large 

 proportion as to render it almost valueless. 



There are few foreign matters usually mixed with magnetic iron ore that appear to exert 

 any injurious effect vipon it in the process of reduction, unless they are in considerable pro- 

 portion. Sulphur is probably the most common of all these substances, but many of our most 

 valuable ores contain small portions of it. Quartz, hornblende, feldspar, pyroxene and mica, 

 are only so far objectionable as that they require larger quantities of fluxing materials and an 

 increased expenditure for fuel. Even titanic acid, which some have thought to be exceedingly 

 deleterious, does not in reality seem to be so, unless the proportion be large ; for it is found 

 in the slags of some of the most largely and profitably worked furnaces, both here and abroad. 

 These facts are especially worthy of notice, because they lead to the conclusion that the 

 quality of an iron depends perhaps as much upon the mode of manufacture employed as upon 

 the kind of ore. 



Chemical analyses of iron ores, and indeed of most other ores, are usually open to the ob- 

 jection that specimens of greater purity are operated upon than the average produce of the 

 locality. It is in this way that incorrect opinions have sometimes been formed in regard to 

 the value of ores, which have at length proved to be the cause of loss and perhaps ruin to 



