COPPER 153 



junction with diabase. These include the New Jersey ores, vigor- 

 ously worked before the Revolution. They consist of the carbon- 

 ates, of cuprite and native copper, disseminated through sand- 

 stone near the trap. The Schuyler mines, near Arlington, N. J., 

 and several other openings near New Brunswick, N. J., are best 

 known. These Triassic diabases often show chalcopyrite, and it 

 is probable that the copper came from this or from copper in the 

 augite of the rock, in accordance with Sandberger's investigations. 

 The deposits are unreliable, and except at a very early period 

 have never been an important source of ore. 



2.04.31. Example 2lb. Contact deposits in sandstones at the 



FIG. 40. Cross section of the Schuyler Copper mine, New Jersey, a, 



trap; b, sandstone; c, shales; the black shading, copper ores. 



After N. H. Darton, U. S. Geol. Survey, Bull 67, p. 57. 



junction with gneiss. A number of deposits were formerly 

 worked of this character, especially at Bristol, Conn., and at the 

 Perkiomen mine, Pennsylvania. The mine at Bristol, Conn., is a 

 well-marked contact deposit, on the line between the Triassic 

 sandstone and the schistose rocks. The contact runs northeast and 

 southwest, has suffered great decomjlbsition from mineral solutions, 

 and has been largely kaolinized. A broad band of this decomposed 

 material, 30 to 120 feet wide, lies next the sandstone and contains 

 disseminated ore. Then follow micaceous and hornblende slates, 

 often with horses of gneiss. The slates are much broken by 

 mpvements that have formed cavities for the ores. It is reason- 

 able to connect the stimulation of the ore currents with the 

 neighboring trap outbreaks. Unusually fine crystals of chalco- 



