176 KEMP'S ORE DEPOSITS. 



which appears at various points. The granite is not always con- 

 tinuous, and is often in isolated masses or horses, as in the Trotter 

 mine. There is also in some portions of the belt a curious scapo- 

 lite rock, regarded as igneous. It is not unlikely that the great 

 dikes may have been a factor in the formation of the ore, although 

 this is not demonstrated. At Franklin Furnace the crystalline 

 limestone forms a low hill (Mine Hill) east of the upper waters of 

 the Wallkill, and again at Ogdensburg, two miles south, another 

 (Sterling Hill), on the west bank. There is a valley and unex- 

 posed strip between, so that the unbroken continuity without a 

 possible intervening fault cannot be established. The bed at 

 Franklin outcrops on the west side of the hill. It begins on the 

 north just across the Hamburg road and runs south 30 west as a 



FIG. 45. Section at Franklin Furnace, N. J., showing the geological re- 

 lations of the franklinite ore body. After F. L. Nason, Geol. of 

 N. J., 1890, XIV., p. 50. The ore body is in ivhite lime- 

 stone with underlying gneiss. 



\ 



continuous bed for about 2500 feet. This portion is called the 

 Front vein. It contains on the north the old Hamburg mine, 

 then the Trotter mine, and in the southern portion belongs to the 

 New Jersey Zinc and Iron Company. It runs from 8 to 30 feet 

 broad at the outcrop, but swells below. It dips southeast 40 to 60 

 into the hill, and is interbedded in the limestone. In the Trotter 

 mine a wedge or horse of hornblende, augite, plagioclase, and 

 various other silicates enters the bed a short distance. In this 

 horse some of the most interesting minerals have been found, such 

 as fluorite, rhodonite, blende (var. cleiophane), smaltite (var. 

 chloanthite), axinite, etc. At the end of the Front vein or, more 

 properly, bed a branch or bend strikes off at an angle of 30 to 40 

 to the west. This more easterly branch, which is called the Buck- 

 wheat mine, outcrops on the surface some 500 feet, and then, after 

 being cut by a trap dike 22 feet wide, pitches down at an angle of 

 27 and passes under the limestone. The portion of the mine north- 

 east of the dike furnishes the most and best ore. The surface out- 



