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state in which it is more usually met with, however, mingled 

 with a greater or less proportion of extraneous mineral matter, 

 the amount of metallic iron contained ranges between 60 and 

 72 per cent. It is magnetic, being endowed with the property of 

 attracting soft iron, and afiecting the magnet. Masses of it are 

 frequently met with possessing a distinct magnetic polarity, the 

 opposite ends manifesting a repulsive action upon the corre- 

 sponding ends of the needle. Such specimens are termed 

 loadstones. 



Though the pure variety is often massive, and mingled with 

 but little foreign mineral matter, yet this is really less productive 

 in the manufacture of iron than the granular or imperfectly 

 crystalline kind, in which we find a moderate proportion of 

 small crystals of hornblende, felspar, quartz, and other minerals, 

 interspersed with the ore. Some of the ore contains a small 

 proportion of titanium. The veins often exhibit a tendency to 

 cleave by numerous natural joints, extending across from one 

 wall towards the other; a structure which suggests a strong 

 analogy to the horizontal columnar arrangement seen in many 

 vertical dykes of lava and basalt. This, if the proofs already 

 cited were not enough, deserves to be regarded as an argument 

 in behalf of the opinion that these veins of ore have been injected, 

 while in a fused or molten state, into the gneiss, and are not in 

 the strict sense beds formed contemporaneously with the surround- 

 ing rock. 



This point, though at first sight unimportant, and seemingly 

 one of mere theory, is of much practical moment to the miner, 

 since it acquaints him with the nature of the veins in which he is 

 operating. 



Local Details. — In offering a detailed description of the veins 

 of magnetic iron ore as far as they have been developed, we 

 shall begin, for the sake of convenience, with those lying towards 

 the northeast. The first which claim our attention are those of 

 Pompton township, in Bergen county. The principal veins of 

 this tract occur in the continuation of the Sterling Mountain of 

 New York. In the ridges immediately west of the Ringwood 

 Valley at least two extensive veins are known. 



The most southeastern of these has been explored for much the 

 greatest distance, several mining excavations having been made 



