178 KEMP'S ORE DEPOSITS. 



the north with the New Jersey Zinc and Iron Company's property 

 and runs south 30 west for 1100 feet. It then branches or bends 

 around to the west and runs north 60 west for 300 feet, bend- 

 ing again to north 30 east, and pitches beneath the surface. 

 Thus the general relations between the front and back beds 

 are somewhat the same as at Mine Hill, and the dip and pitch 

 are similar. The principal workings are on the Front vein, where 

 there are two veins (beds), according to the older descriptions, one 

 rich in franklinite and the other in zincite. It is doubtful if there 

 really are two distinct beds, but probably one portion is richer in 

 zincite than the other. The part mined is from two to ten feet. 

 The footwall is corrugated and causes many pinches and swells, 

 whose troughs pitch north. The limestone between the front and 

 back outcrop is charged with franklinite and various silicates (jef- 

 fersonite, augite, garnets, etc.), and has been mined out in large 

 open cuts now abandoned. A deposit of calamine was found in 

 the interval about 1876, and has furnished many fine museum 

 specimens. 



2.07.07. It is not clear that the Sterling Hill and Mine Hill 

 deposits were once continuous. The bed at Mine Hill runs in the 

 front portion close to the contact of the white limestone and the 

 gneiss. The Sterling Hill bed is much farther away from the 

 gneiss, and this would indicate that it is at a higher horizon. The 

 evidence, too, of a pitching syncline is strong, but a pitching S-fold 

 is not as clear. A faulting of the Archaean rocks in an east and 

 west line across their strike, and a subsequent tilting so as to give 

 them a northerly pitch, is a very widespread phenomenon in the 

 Highlands, and lends weight in this instance to the idea that a fault 

 intervenes between the two hills. Such faulting is shown even in 

 New York City. 



2.07.08. The origin of these beds is very obscure. They are so 

 unique in their mineralogical composition that very little direct 

 aid is furnished by deposits elsewhere. At Mine Hill, below the 

 fork of the franklinite bed, there was formerly a large lense of 

 magnetite that has now been mined out. It was in the white 

 limestone. There are many points of analogy between the frank- 

 linite beds and extended magnetite deposits. They are both min- 

 erals of the spinel group, and the spinels are a common result of 

 metamorphic action. The presence of zincite and willemite com- 

 plicates matters, however, and while an original ferruginous de- 

 posit might be conceived with a large percentage of manganese, 



